Feels like this toy deserves an award.
True to his name, Darwin has the power to adapt against any threat, be it searing volcanic heat or the cold vacuum of space.
Or anything else at all, really, but it isn't always helpful: remember, the idea is to adapt to keep him safe, not to necessarily do the same for anyone else. So like, one time the X-Men were fighting the Hulk, and initially Darwin developed the ability to drain gamma energy away from Hulk, weakening him; but when Hulk punched him, instead of just becoming super-resillient or something, Darwin's body decided the best way to survive this was to simply teleport him away from the battle entirely. Whoops! [Whoopsie! --ed.] He doesn't get to consciously decide how he's going to survive something, he just survives it.
Armando Munoz was one of those mutants who was different from birth, rather than having to wait for puberty. He wasn't quite into Morlock territory, but his eyes were overly large, his limbs were longer than usual, and he was completely hairless. By the time his actual powers kicked in, his eyes turned blank white, and his head almost looked like a stereotypical alien's.
This is basically "corner-cutting, the action figure." Darwin's entire schtick is that he's constantly changing, but the
only thing we get is an alternate pair of hands that are slightly larger than usual? They're good, but they're alone. Even if Hasbro was just going to give us hands and nothing else, we should have gotten a bunch in different colors and textures. Yes, a lot of times his changes are not obvious - becoming immune to lasers doesn't look any different than being vulnerable to lasers - but there had to be some way to show off what he can do.
To portray his lanky frame, Darwin is made on the skinny Spider-Man body. And hey, those big doofy feet help make him look less human, too! Originally under the care of Moira MacTaggart, Darwin eventually got months of emergency mental training in just a few hours, and received an X-Men uniform: mainly dark blue, with purple sections on the sides and the arms. The belt and sections right near the wrists are a slightly different shade of purple than the rest, though it's hard to notice.
The Build-A-Figure for this series is Bonebreaker, and Darwin includes one of his legs. Er, tank treads.
Darwin is an unlikely choice to get a Marvel Legend, being both fairly obscure and fairly un-toyetic, but here he is regardless. The alternate hands suit him better than the fists do, and his bald head and unusual colorscheme will help him stand out on your shelf. And honestly, this head would be perfect to reuse for the Skinny Caliban we've propsed before.