Thanks to Nitsuja for these damage values:

The damage numbers are PER HIT, although some moves can hit 2 or 3 times. I put a ¤ after the ones that might hit twice if you're good, and a ¤¤ after the ones that are pretty likely to hit twice if the enemy allows it.

Most testing was done against Super Shredder in Hard mode, although I'm pretty sure it transers to other bosses and modes, with the possible exception of multiple hit notes since they depend on how long the boss is invulnerable between hits.

Raph (sai): attack 1: -5 (down slash) attack 2: -4 (wide slash) attack 3: either -3 (pull slash) or -5 (stab), randomly chosen attack 4: -8 (whirling sai stab) jump+attack 1: -4 (upward kick)¤¤ jump+attack 2: -4 (diagonal downward kick) jump+attack 3: -6 (lifting sideways kick) jump+attack 4: -8 (floating downward slash)¤ special: -16 (spin kick, uses health) dash+special: -16 (hovering slide kick) dash+attack: -10 (shoulder ram) post-ram attack: -12 (standing kick) dash+jump+attack 1: -14 (ground slide dash) dash+jump+attack 2: -20 (looks like shoulder ram but does 2x damage)¤

Mike (nunchucks): attack 1: -5 (down swing) attack 2: -8 (wide swing) attack 3: -8 (whirling upward swing) attack 4: -10 (forward swing) jump+attack 1: -3 (upward kick)¤¤ jump+attack 2: -3 (diagonal downward kick) jump+attack 3: -6 (lifting sideways kick) jump+attack 4: -10 (floating downward swing)¤ special: -12 (leaping side-swing, uses health) dash+special: -10 (hovering slide kick) dash+attack: -8 (shoulder ram)¤ post-ram kick: -8 (standing kick) dash+jump+attack 1: -10 (ground slide dash) dash+jump+attack 2: -16 (looks like shoulder ram but does 2x damage)¤

Don (bo): attack 1: -3 (down swing) attack 2: -4 (wide swing) attack 3: -6 (forward bo stab) attack 4: -8 (spinning bo) jump+attack 1: -3 (upward kick)¤¤ jump+attack 2: -4 (diagonal downward kick) jump+attack 3: -4 (lifting sideways kick) jump+attack 4: -14 (floating downward swing)¤ special: -14 (weird vault kick, uses health)¤¤ dash+special: -12 (hovering slide kick) dash+attack: -7 (shoulder ram)¤ post-ram kick: -9 (standing kick) dash+jump+attack 1: -10 (ground slide dash) dash+jump+attack 2: -16 (looks like shoulder ram but does > 2x damage)¤

Leo (swords): attack 1: -4 (down slash) attack 2: -5 (wide slash) attack 3: -6 (forward stab) attack 4: -8 (floating down-thrust)¤¤ jump+attack 1: -3 (upward kick)¤¤ jump+attack 2: -4 (diagonal downward kick) jump+attack 3: -6 (lifting sideways kick) jump+attack 4: -8 (floating downward swing)¤ special: -8 (spinning swords, uses health) dash+special: -12 (hovering slide kick) dash+attack: -8 (shoulder ram)¤ post-ram kick: -9 (standing kick) dash+jump+attack 1: -10 (ground slide dash) dash+jump+attack 2: -16 (looks like shoulder ram but does 2x damage)¤

Other damage: slammed on ground: -4 (per slam) (may also insta-kill after 3 or 4 slams) slammed by another enemy: -32 hit by power pizza spinning: -32 ¤¤ hit by giant bowling ball: -16 ¤ hit by a screen-tossed enemy: -10 (to shredder) getting tossed (stone warrior): -12 hit by a tossed stone warrior: -24

Turtles Summary:

Best at regular attacks: Mike Best at downward jump attacks: Don Best at upward jump attacks: Raph Best at special attacks: Raph Best at dash attacks: Raph Best speed: Raph, 2nd-best is Leo Best defense: Mike, 2nd-best is Leo

Worst at regular attacks: Raph Worst at upward jump attacks: Don Worst at special attacks: Leo Worst at ramming: Don Worst at slide-dash: Mike Worst speed: Don, 2nd-worst is Mike Worst defense: Raph, 2nd-worst is Don

HP totals of enemies: -purple punching dude: 16 [Personally, I've noticed two different values in the first level.] -blue fork dude: 20 -pink shuriken dude: 20 -white nunchuck dude: 20 ¤baxter: 96 -blue sword dude: 24 -red knife dude: 28 or 24 -roadkill rodney: 16 ¤metalhead: 128 -sewer dudes: 2? -pizza monster: 3 ¤rat king: 96 -mouser: 1 -pink shield dude: 16 or 12 ¤tokka: 96 ¤rahzar: 96 -dudes on elevator: abnormal customized HP values ¤shredder: 90 -blue axe dude: 32 -stone warrior: 40 -yellow bomb dude: 2 ¤slash: 160 -green archer dude: 2 -yellow frisbee dude: 24 -stone warrior with cannon: 40 ¤rocksteady: 128 ¤bebop: 128 -red grappling dude: 16 ¤leatherhead: 172 -hoverboard dude: 2 -n.n. mousers: 2 -copter dudes: 2? ¤super krang: 192 -security bot: 2 -robot walker: 3 -stone warrior with flame gun: 2 or 40 -stone warrior with laser gun: 40 ¤krang: 128 ¤super shredder: 248