...is much lower than that of the people around him. But you've given him a "turtle suit" to make up for this.

It seems a bit odd that you would do this, because it sort of defeats the purpose of having a non-super in a group of supers. You've given him tech-based powers, essentially making him just one more Turtle. The suit simply doesn't fit with the stealth theme, either. It's too flashy. If I were you, I'd drop it.

Shurikens are another problem. Yes, they fit the Turtle theme, but they're entirely too obvious. If he's going to blend into a crowd, becoming a near-invisible stealth/scout type, he needs to have weapons that aren't so obviously unique to him. Knowing how to throw shurikens accurately makes sense, considering his adopted family; but his using them regularly in the field does not.

He's a human among mutant animals. Being human, his biggest asset is his intelligence. Don't make him utterly gifted, but give him the ability to strategize and plan. Make him Splinter's apprentice--Splinter is the strategist of he group, and he'd have the most to teach this (I'm assuming teenage) kid.

Lastly, you have a power set here, but you don't have much of a personality. Technically, you don't have a character yet. Ask yourself: What is it like growing up as a human among non-humans? Does he envy normal humans, or is he confused by them, or does he identify with them? How well can he blend in; does his odd upbringing give him trouble? What does he like to eat? What does he do with his free time? Does he have a favorite author, a favorite musician?

For that matter, how did he learn how to read? Did he go to school? Unlike the Turtles, his normal appearance would have allowed it. If not, how did he learn about the world around him? Does he have a role model? Has he ever fallen in love? What does he want to be when he grows up? Does he have talents for something other than martial arts? Hobbies?

Does he wonder who his birth parents are, or does he think of his adoptive family as his real family to the point that his birth parents aren't really something he cares about much? Does he have a false identity that will let him pass among humans? What would happen if he had to have a cavity filled or his appendix taken out?

This is an interesting idea for an OC, but it needs more work to keep it away from Studom. You don't want yet another Turtle, albeit in a human suit; the existing Turtles fill that role just fine. Instead, give him his own path, his own story to tell.

Also, welcome to the PPC...sort of. Here's a bo staff, use it wisely.

Can you please use line breaks? I see a massive wall of text which causes my eyes to keep sliding off it.