Mikey can fly, but he must abandon his legs from the knee down to do so. (dont worry he can reattach them -or regrow them if he had to, though he prefers not to, it takes way too long)
He has no upper arms, he traded them for another pair of lower arms/hands, which can all move independently if his body. (and chuck fireballs) When hes not actively using them, they orbit his body like the blaze rods in the blaze.
His skin is normally hot to the touch, and much hotter at the joints. But generally its not painful to the touch, its when he gets emotional that it gets dangerous (which is literally all the time)
Snow is his worst enemy. he hates that shit. absolutely evil.
His shell is constantly evaporating and reforming. Probably because it looks cool.
Mikey and Donnie are the only two who can really live comfortably in the nether for a long amount of time. Mikey likes taking long lava baths there, and trading for exotic ingredients.
He can retract back into his shell, which along with his plastron are the most solid part of his body. the rest of his flesh is suspiciously goopy.
it is a common prank to steal Mikey's limbs whist he's distracted. Leo is the most common offender here.