Fastest Jungle Level 1 - 6 and Gank?

Xin is pretty good for it to. I think he would be a little slower to hit 6 than WW but definitely up there.

All melee auto attackers with some sort of sustain. Udyr and Master Yi come to mind

Yi kind of gets bullied early jungle though. Or at least without a specific rune and mastery page he does.

cho could clear jungle and never back all game but he needs to back before he ganks cuz after blue wears off his mana tends to stay kind of low at least when i play him

Not Nunu btw, it's impossible to gank a bottom lane with him as most supports should have some type of hard CC