How good is Martian ManHunters Shapeshifting?

Can he for example turn into a superman (a.k.a a kryptonian) and absorb the sun's radiation to boost his stats?

Can he shapeshift his brain to be exactly like batmans gaining his knowledge, memories, and skills ?

Can he completely change his biology to another species? Or even change his sex?

He can't do the first two, even if he could he wouldn't be able to hold those kind of changes for long but other than that he can copy animals, people and change his shape

Good enough

Pilasy:La Voix d'un homme

He can't, or at least hasn't, done anything like the first.

Not in the way you describe, which is not how it works anyways, the brain doesn't change shape in accordance to personality and memories. He can copy Bruce's personality, memory and skills through telepathy and mimic his physical appearance. However, he did in the pages of JLA mimic the condition of the Joker's mind once in order to navigate a labyrinth designed by him.

I wouldn't imagine he could, because in doing so he would loose all of his Martian abilities. I mean if he turned completely human, he would loose everything that made him Martian and unable to turn back. He can look, talk and walk like a human, but he will always be a martian on the inside. In regards to females, he can look like them... but no, he is not going to be able to make babies.

I think he can do the last part given that he once copied Wonder Woman down to her nervous system

http://www.comicvine.com/images/1300-1720704/

@ultra_supermanking: he has shapeshifted his brain to think like the joker if I recall correctly. I don't think he can change into a a kryptonian and utilize their power though

He can change any part of himself on the molecular level.

Physical properties only, no chemical property changes. So he can make a bunch of weapon limbs but can't make the same isotope as kryptonite/lead to hurt Kryptonians/Daxamites

He can do the second via telepathy I'd think. I don't think someone can shapeshift a brain to have memories though, as the memories in the brain are based off biochemical reactions, not shape.

Not as good as the skrulls

@ultra_supermanking: just ask your mom how GOOD his shape shifting is.

@benk111: I think he is a better shape shifter than the average skrull