Here's my TMNT Hack for The Vigilante Hack in action.
Class: Martial Artist
Hit Points: 12
Armor: Light (2 points) - from rear attacks only
Attack Damage: 1d8/1d6 Unarmed
Special Features: Because of his life time of training with Master Splinter, Leo +1 on all Melee combat rolls. In addition, because he's a mutant turtle he can hold his breath underwater for 10 minutes, gains advantage on swim checks, is considered to have light armor when attacked from behind, and suffers disadvantage on non-intimidation social rolls.
Weapons and Equipment: Twin Katana
I would say he's on par with your average 1st level vigilante. Yes he's going to do well in situations involving water, but then again if he's trying to calm a citizen or talk his way out of a problem, he's going to have issues.