This alien  was presumably recruited to Colosseum to participate in the Great Games, although it is possible he could be part of the service staff, or perhaps a spectator who happened to be in the wrong place at the wrong time. During the night of recreation/celebration after the first day's battles, the green-skinned alien ended in a fight or was just attacked by Terran super-villain Sabretooth, who savagely beat him.

    Wolverine broke up the fight to recruit Sabretooth to join their plot to prevent the Battletide from destroying the universe.

(Battletide#4 - BTS) - The Battletide washed over Colosseum, overwhelming the spectators and most of the remaining combatants. Dark Angel and Psylocke formed mystic shields to protect the heroes' minds, allowing them to fight off those under the Battletide's influence.

    Termagent and Megaira merged back into their previous self, the powerful Termagaira.

    While Death's Head and Killpower confronted Termagaira, the others were left to fend for themselves against the Battletide-controlled horde.

(Battletide#4) -  Psylocke used her psi-blade to incapacitate but not kill a green-skinned alien.

--BattleTide#4

     Large, muscular and green, with a top-knot/fore/mid-lock of hair and pale blue-green skin, he wielded some giant spikey-mace deal.

(Battletide#4 - BTS) - The Battletide washed over Colosseum, overwhelming the spectators and most of the remaining combatants. Dark Angel and Psylocke formed mystic shields to protect the heroes' minds, allowing them to fight off those under the Battletide's influence.

    Termagent and Megaira merged back into their previous self, the powerful Termagaira.

    While Death's Head and Killpower confronted Termagaira, the others were left to fend for themselves against the Battletide-controlled horde.

--BattleTide#4

Two of the combatants in the Great Games, willing or not:

     The tall purple crustacean creature (on the left of the image) had apparently four arms on each side of its thorax (with at least one on each side with pincer-like claws), large spike projection from the top and bottom of its head, sharp fangs from at least the upper jaw, toe legs, and a tail.

     The shorter combatant (on the right of the image) had red skin, pointed ears, and was apparently prognathic (having under underbite, with prominent mandibular (lower jaw) canine teeth. He carried a pair of hand blasters able to rapidly fire apparent laser beams (which could apparently penetrate Death's Head's head.
     The blasters made a "THRAKKA!" sound.

(BattleTide#2) - Shortly after Death's Head and Killpower were transported to Battle Zone One, the crustacean and prognathic combatants burst through a brick wall and assaulted them.

(BattleTide#2 (fb) - BTS) - Death's Head and Kilpower apparently defeated (and presumably slew) these combatants, as they soon faced and defeated a series of subsequent combatants.

--BattleTide#2

Note: As the contest was to the death, I'd expect both of these guys to have perished, since Death's Head and Killpower survived to take out numerous other combatants throughout the day.

The smaller guy reminds me of Star Wars' Snaggletooth...or maybe one of the characters from the Laugh-A-Lympics' Really-Rottens team...

If I were to name them, I think I'd go with Pincer (or Pinsur, or Crustac) and Pronath.

     The green-armored combatant wore highly durable armor that enabled him to shrug off various ballistic charges from Killpower, to survive behind directly under a collapsing large stone archway (although it did knock him to the ground), and to be unphased by having a 4-6" thick wooden log swung by the superhumanly strong Killpower (the log broke off against his armor, while the warrior was not even physically moved by the impact).

     However, he was much more vulnerable to bladed weapons (at least those made out of whatever Death's Head's blades were made of)

     He was superhumanly strong, and he could hysically throw off several hundreds of pounds of stone piled atop him. Additionally, he could launch the spiked mace on his right wrist with explosive force. He had no hands, and while he had spiked maces on both wrists, he was only shown to launch the one on the right side; it is unrevealed whether he could launch the spiked mace from his left wrist. He could presumably reattach the spiked mace after launching it, but it either didn't automatically return to him, or Killpower collapsed the archway on him before it could return to him.

(BattleTide#2) - By nightfall, in Battle Zone One, after Death's Head and Killpower had taken out enough combatants to be described as "knee-deep in fallen opponents," they faced off against the green-armored combatant and "Jellyhead."

     Killpower was exasperated as the armored warrior weathered everything he had to give and continued to assault him.

     Similarly frustrated, Death's Head suggested they swap opponents.

     Death's Head swiftly and repeatedly stabbed the armored warrior in the chest, releasing large volumes of blood (presumably) and leading to the warrior's apparent demise. 

    Killpower swiftly destroyed "Jellyhead."

--BattleTide#2

Note: This combatant is also shown in the bottom right image of the main profile.

     As the contest was to the death, I'd expect both of these guys to have perished, since Death's Head and Killpower were confronted by their next combatants as soon as these two fell.

    Similarly, as they faced Death's Head and Killpower toward the end of the day's combat, it would seem that they likely took out multiple combatants before facing those two.

     Called "Slimeball" by Death's Head and "Jellyhead" by Killpower,  he gray creature with short tentacles appeared to be similar to a Medusazoan (jellyfish) or Actinarian (including sea anemone). It appeared to be composed entirely of those short tentacles, and it lacked any obvious internal organs. If cut apart by lasers or blades, it could just reassemble itself. However, a sufficiently powerful explosive device could blow it to pieces and destroy many of its tentacles; and it all of its tentacles were destroyed, that was sufficent to destroy it.

     "Jellyhead" could compress/flatten or extend itself, altering its height/width signficantly, and it could also grab an opponent, swinging him/her/it up over itself and smashing it to the ground on the opposite side with great force.

(BattleTide#2) - By nightfall, in Battle Zone One, after Death's Head and Killpower had taken out enough combatants to be described as "knee-deep in fallen opponents," they faced off against the green armored combatant and "Jellyhead."

     Death's Head was frustated as the "ugly spoor" ("Jellyhead") recovered from his assaults, even when he sliced it into pieces, and continued to batter him.

     As Killpower was similarly frustrated, Death's Head suggested the swap opponents.

    Killpower fired an explosive round into "Jellyhead," blowing it apart, after which he stomped on the tentacles that still flopped around until there weren't any more.

Meanwhile, Death's Head's bladed weapons took out the green-armored warrior.

--BattleTide#2

Note: This combatant is also shown in the bottom right image of the main profile.

     As the contest was to the death, I'd expect both of these guys to have perished, since Death's Head and Killpower were confronted by their next combatants as soon as these two fell.

--BattleTide#2

Note: As the contest was to the death, I'd expect both of these guys to have perished, since Sabretooth and Wolverine survived to go on to face other combatants.

     I'd guess they shot up Sabretooth and Wolverine, dropping them, but then the mutants' healing factors allowed them to recover and take out the two shooters.

    A combatant in the Great Games, willing or not, he was partnered with the death-locust thing

     A brown, semi-humanoid biped, he looked to have three clawed fingers and a thumb on each hand, with two toes on each foot. He had a pair of ears with pinnae like hoofstock, pointed in the posterior direction. He appeared to have composite eyes, like an insect.

     He had a pair of long, horn-like projections pointing in an inferior and lateral direction (down and out), as well as a pair of smaller, curved horns/spikes projecting from the corners of his mandible (lower jaw).

     He seemed to lack an external nasal structure.

     He had numerous sharp teeth, which apparently did little to dissuade him from letting his long, pointed tongue hang out of his mouth most of the time.

(BattleTide#2 - BTS) - Transported to the Oasis sector, he hid within a tree in preparation for an ambush.

(BattleTide#2) - As Dark Angel and Smith approached the trees, this combatant dove out of tree at Smith. Either via warning from Dark Angel or his own instincts, Smith tumbled out of the way, causing his attacker to hit the sand.
As this combatant extended his wrist blades, Smith formed a lash-like weapon, which he then whipped around his attacker before releasing a devastating energy blast.

--BattleTide#2

Note: As the contest was to the death, I'd expect this guy and his partner to have perished, since Smith and Dark Angel survived to continue in the Games.

     He wore a cape with a distinctive symbol on it, although I don't know what it is meant to signify.

      A combatant in the Great Games, willing or not, it was partnered with the wrist-bladed combatant.

      This creature was some form of death-locust...or killer sand flea...or something. It had paired antennae, at least four four pointed limbs, sharp, fanged teeth, and an armored, chitinous exoskeleton.

(BattleTide#2 - BTS) - Transported to the Oasis sector, this combatant buried itself in the sand in preparation of an ambush.

--BattleTide#2

--BattleTide#3

    The green combatant had wings extending from wrist to ankle, somewhat like the wings of a bat, enabling flight
    Its face is hard to describe, so just check out the image to the right.

    The silver-gray combatant either appeared to be robotic or perhaps was completely covered in armor  (it looks more robotic to me)
    Its wing arose from its back, enabling flight.
    It had sharp teeth running
    It had spikes running from the center of its fact over the top of its head and down the length of its tail.

(BattleTide#2) - In an identified battle zone, the two winged combatants ambushed Hercules and Psylocke, casting weighted nets at them.

    While Psylocke's alertness and quick reflexes allowed her to dodge her net, Hercules was caught.

    As the winged combatants circled overhead, Hercules demanded the "cowardly dogs" release him.

--BattleTide#2 (3

Note: Another image of the winged combatants is shown in the Colosseum profile's Battle Zone "Four" sub-profile.

    As the contest was to the death, I'd expect both of these guys to have perished, as Hercules and Psylocke survived to continue in the Games; however, it is possible the heroes just claimed victory and allowed their opponents to survive.

--BattleTide#2

Note: Despite Tasker's instruction that if one combatant died the other would be slain by the collar, we saw multiple examples of one combatant being slain while the other continued to fight. Perhaps most other combatants were willing, and only the Earth-derived group and Smith needed the collars?

     The immense mothership had an aperture at its base through which the shuttle could enter, after which it closed via six converging spikes.

    The mothership was covered in a number of spikes, but when it prepared to fly, the spikes would compress to make it more aerodynamic...although it was, of course, flying through the vacuum of  space.

     The mothership flew through space and could also achieve warp speeds. It transported the shuttle to a distant orbit of a planet, after which the shuttle was released to enter the planet's atmosphere and capture targets.

(BattleTide#2) -  After the shuttle had collected and placed in stasis Dark Angel, Death's Head, Hercules, Killpower, Psylocke, Sabretooth, and Wolverine, the shuttle then flew into the massive mothership, which then warped away, delivering them to Colosseum.

--BattleTide#2

Note: I would speculate that a single mothership carried inhabitants of numerous shuttles to Colosseum.

     Those aboard the shuttle released into Earth's atmosphere included the acquisition leader, a number of marshals, and Termagent and Megaira (although they could have teleported from the mothership).

     The shuttle included a tractor beam to lock onto and transport targets into its interior; stasis tanks able to contain powerful captives; nullifiers to neutralize superhuman abilities; the means to locate specific beings on a planet; the means to apparently teleport beings to and from its interior to and from specific locations;

     The immense mothership had an aperture at its base through which the shuttle could enter and depart.

     The shuttle dwarfed the island of Kamuni Atoll.

(BattleTide#1 - BTS) - After the shuttle departed the mothership in Earth's orbit, it flew into the atmosphere and apparently teleported Psylocke and Wolverine aboard from a rock tower they had scaled in the Appalachian mountains.

(BattleTide#1 (fb) - BTS) - Wolverine and Psylocke were placed into containment tanks.

(BattleTide#1 (fb) - BTS) - At some point, Sabretooth and Hercules were captured and placed into containment tanks.

(BattleTide#1 (fb) - BTS) - A purple creature was teleported into a sensory deprivation tank containing Dark Angel; as the creature struggled to capture her, the shuttle's nullifiers proved insufficent to contain her until the acquisition leader had the power boosted to omega levels to maintain the containment field. These increased levels allowed Dark Angel to be subdued.

(BattleTide#1 (fb) - BTS) - Dark Angel was transported into the shuttle and placed into a containment tank.

(BattleTide#1) - Flying above the Kamuni Atoll island in the South Pacific, the shuttle locked onto Death's Head with a transmat beam; however, as Death's Head was in the midst of a battle with Killpower, he was transported as well.

(BattleTide#2) - Death's Head and Killpower fought off marshals seeking to contain them; ultimately Termagent and Megaira subdued the pair.

The shuttle then departed Earth's atmosphere and boarded the mothership, which transported it to Colosseum

After arriving on Colosseum, combatants were contained within yellow energy globes that allowed movement but prevented escape.

Tasker floated on a hoverdisc in front of a number of viewscreens with the "invited" combatants in containment spheres, and he addressed the record-level crowd, reviewing the history of the Games and announcing that this year would be the most spectacular and ruthless Games ever held, as this year, they were to the death.

--BattleTide#2

Note: In addition to the known beings within the globes, from the main image there are a number of partially sen combatants.

     We know nothing beyond what you can see visually here, so I'll just leave it at that. I'd love some back-story info on these guys...

The marshals facilitated and served as enforcers in the Games.

Large (perhaps 8' tall), broad, and strong, they wore red body armor with their faces exposed. They had small, dark eyes, no external nasal structure, and were somewhat prognathic, with their mandibular canine teeth projecting out of their mouths.

(BattleTide#1 - BTS) - Aboard the shuttle in Earth's atmosphere, Marshals presumably assisted the acquisition leader in locating, capturing, and containing Dark Angel, Hercules,  Psylocke, Sabretooth, and Wolverine; and transporting aboard Death's Head and Killpower.

(BattleTide#1) - As one of the marshals checked on the captives, another marshal announced to the acquisition leader that they had completed their collection and confirmed their captives' identities, although there was a potential error in that they had detected a body weight anomaly.

     The acquisition leader noted this to be irrelevent and that the marshal should inform Termagent that the contestants from Earth were now on their way to Colosseum.

(BattleTide#2) - A number of marshals struggled against Death's Head and Killpower, seeking to contain them.

     Marshal 386 contacted the bridge, noting that the weight anomaly had been explained as they had acquired a second specimen along with Death's Head. As he requested immediate back-up, Death's Head extended a spike through his head, killing him.

     Death's Head and Killpower continued to overpower the marshals until Termagent and Megaira subdued the pair.

     At Termagent and Megaira's instruction, the marshals then placed Death's Head and Killpower in stasis alongside the others.

(BattleTide#2 - BTS) - The shuttle subsequently entered the mothership and was transported back to Colosseum.

(BattleTide#3 - BTS) - The marshals supervised the combatants night of relaxation in the Pleasuredome.

(BattleTide#3 - BTS) - The Temploids apparentlly mystically cloaked from the marshals the departure of the terrestrial participants and Smith from the Pleasuredome when they departed to meet with the Temploids.

(BattleTide#3) - After the terrestrial heroes and Smith freed themselves from their inhibitor collars, the marshals fought futilely to subdue them. When Termagent and Megaira arrived to prevent any escape, the Marshals stood by them.

(BattleTide#4) - As the Battletide descended on Colosseum and merged with Termagent and Megaira, the marshals stood in shocked surprise.

     Like the spectators, the marshals presumably fell under the Battletide's influence, seeking to slaughter those who resisted them.

(BattleTide#4 - BTS) - The marshals were not seen after Termagaira and the Battletide were destroyed.

--BattleTide#1; (identified) BattleTide#2 (3 - BTS, 4

(BattleTide#2 (fb) - BTS) - Per Tasker, "Every three cycles (see comments), warriors from across the multiverse were invited to Colosseum to participate in the greatest blood sport of them all...the Games."

     Spectators observed each performance of the Games in some fashion.

(BattleTide#3 (fb) - BTS) - The "Omniversal Transmitter" in the Tower provided a direct link to viewing channels of the populated cosmos.

(BattleTide#2) -On Colosseum, Tasker floated on a hoverdisc in front of a number of viewscreens with the "invited" combatants in containment spheres, and he addressed the record-level crowd, reviewing the history of the Games and announcing that this year would be the most spectacular and ruthless Games ever held, as this year, they were to the death.

     The crowd cheered as Tasker iintroduced the Games' all-time champion team, Termagent and Megaira, and as the games commenced and the combatants were transported to their various battle zones.

(BattleTide#3) - At the conclusion of the first day of contest, Tasker re-collected the combatants and transmitted to the spectators how the combatants would enjoy a night of supervised relaxation before tomorrow's free-for-all bout.

(Battletide#4 - BTS) - The Battletide washed over Colosseum, overwhelming the spectators and most of the remaining combatants.

    Dark Angel and Psylocke formed mystic shields to protect the heroes' minds, allowing them to fight off those under the Battletide's influence.

--BattleTide#2 (3-4

Note: Other spectators are seen in the main profile here and in the Colosseum profile here: