The sheet is very very good but my only concerns are with powers. His first two abilities are pretty damn potent already, I'm not convinced the latter three could be included without making him overpowered, if he was just like an Earthbender from Avatar that wouldn't be a problem but as his abilities stand so far I'm pretty sure his is literally the most powerful person so far and as such I believe the last three abilities can be taken out or limited even more. 

Also if he's going to turn into stone there should be weaknesses like perhaps extreme heat or water eroding his stone, things like that. As a Superhero RP there's going to be a lot of Physical confrontation so he can't literally be somebody nobody could physically challenge like the sheet says. Also since he's such a gifted athlete I suppose his gymnastic prowess bleeds over even when he's stone making him a lightning bruiser which considering his physical prowess already is problematic. I could buy him being more light and acrobatic out of stone but in stone he should more slow and lumbering to balance things out. 

And he'd need some kind of reason to be associated with the League no matter how tenuous. 

Other than that it is a fine sheet.