Colossus could not transform back to his human self without risking death.
The Colossus from the Deadpool movies is a bit confusing. Not only does he not need to breathe, but doesn't have to eat either. Nor go to the crapper and vomit. Yet, in the film he does all those things and never shows up in human form.
During his time as the Avatar of Cyttorak, Colossus stayed in his steel form. He revealed that the reason for this is that in steel form he is a hero and in flesh form he is a man.
Colossus can only transform his whole body into metal and not individual portions. This means that he cannot discreetly use his abilities, such as hiding them behind clothing. He also cannot maintain his form after he has been knocked unconscious, which means that it is possible to switch his powers off.
That work was led by vfx studio Framestore (a different studio, Digital Domain, had brought Colossus to life for the first Deadpool film). The metal attributes meant a certain kind of 'stiffness' always had to be present, although at the same time Colossus also had to move freely and fight ferociously.
Wolverine's claws are so deadly, that they once managed to cut straight through colossus, whose body is made up of impenetrable organic metal.
The solution to this was…unexpected: Colossus appealed to the mystical source of the Juggernaut's usual power and, in becoming a Juggernaut himself, finally was able to beat the bad guy for once. There was, of course, a drawback: Colossus was stuck being a Juggernaut for a number of years afterwards.
Colossus: The Superhero
Similar to a number of characters in Marvel literature, Colossus has the ability to change his external appearance. His genetic mutation allows him to create an “organic steel” layer, which acts as an impenetrable external shell.
Despite this near-invulnerability, it is still possible to injure him, and if knocked unconscious, Colossus reverts to his human form. In his metal form, Colossus bleeds pure energy when injured, and he has no organs that can be damaged.
Yes. Not only has Magneto turned Colossus into an X-battering-ram many times, he once found Colossus injured and locked into his metal form… and used his magnetism to close those wounds and heal him.
The power granted by his mutant ability has other functions as well. Whilst in his organic steel form, Colossus does not need to breathe. Not only does this allow to survive in the vacuum of space, it also allows him to travel underwater.
It is established that the Flora Colossus hero senses physical pain. While he can grow his limbs and cut them off, he can also grow and reduce their size.
The closest thing the cinematic X-Men have to match the Hulk's strength is Colossus. In the comics, Colossus is strong but not on the Hulk's level. However, the two's most recent cinematic incarnations might just prove that, if the two went head-to-head, Colossus would obliterate Hulk.
But despite his impressive abilities, Colossus isn't remotely close to attaining Omega-Level status. He's resilient but to a fault - as numerous Sentinels and the Hulk have proven. Colossus might night need to breathe or eat when he transforms, but he does become heavy enough to sink in steep bodies of water.
Tim Miller's idea of Colossus was to be bigger and stronger than everyone else, so for the motion capture they needed an extremely tall man. I'm 6-foot-4, but he wanted Colossus to be over 7 feet, so they used a stunt double to recreate his height, and he did very good job there.
Thanos is definitely stronger than Colossus and while his organic steel body would stand up to Thanos's attacks for a while, eventually, Thanos's plasma blasts would be able to melt him or even blast straight through him.
To specify exactly what he transforms into, Colossus's body becomes imbued with the real-world metal osmium, which is the densest stable element, approximately twice as much as lead. Its essentially as tough as diamond, and its melting point is approximately 5491 degrees Fahrenheit.
Colossus isn't as durable as vibranium or adamantium. His skin is some sort of organic steel alloy that can heal but only in his human form I think. With vibranium and adamantium as 2 of the most durable materials in the Marvel universe, Wolverine and Black Panther could likely cut him.
Natural Peak Human: The highest limit a human man can over-head lift is at least 600 lbs, but no more than 700 lbs. For example, Kingpin - 650 lbs, Punisher - over 500 lbs, Colossus - 700 lbs, [citation needed] etc. The highest limit a human woman can over-head lift is at least 200 lbs, but no more than 300 lbs.
Colossus becomes the new Juggernaut! After making a deal with the Cytorrak, the X-Men's strongest member becomes unstoppable, rampaging through the streets of San Francisco. One destructive bender you won't want to miss.
Colossus' age is given, in the comics, as 18 during 1982: Kitty is about five years her beloved's junior.
During "World War Hulk", Hulk (in a show of strength) bent back Colossus' arm, essentially breaking them.
Wolverine, given enough time, could defeat Colossus in a fight using only his claws, but he would have a terrifically difficult time doing so; the latter's skin is made of adamantium, same as Logan's claws, and even a demon-controlled Wolverine can do very little against him.
So while Juggernaut is much more powerful, and would normally be able to win in a fight, Colossus could convince Cyttorak to transfer his power, or even cut off Cain Marko's connection to Cyttorak. Cain Marko would be left as a normal human. Colossus would still be a powerful mutant.
Hulk (2009) #1. While Colossus tends to be the strongest member on any X-Men roster, the Hulk's a bit out of his league. Colossus knew this before he threw his first steel-coated punch, but still entered into a fight with the Hulk anyway. He got in a few good blows, but none of them phased the Hulk.