These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
The SNES game itself can be counted as it is quite popular among tournament fighting game players.
Game Breaker: There are a few moves that are a bit too good. Donatello's strong punch has instant recovery, deals tons of damage, stuns fast, fills um 40% of his special gauge when his life is on red, AND has very good range. The computer can counter this by magic reflexes, but against a human...
Leonardo's Special takes pretty much the whole screen, deals around 50% damage IF BLOCKED and if it hits, deal more than this AND stuns the opponent.
Michaelangelo's Rising Thunder takes over 30% of life if it connects on the ground.
Raphael's biting grab in the NES version can be spammed to make getting through the game trivial.