Cowabunga It Is achievement in Teenage Mutant Ninja Turtles: Shredder's Revenge

From my experience, Mousers are the easiest enemy to do this with.

They do not die as quickly when they hit the ground and they do not bounce around the stage as much as Ninjas.

Corner them against a wall and go to town with the basic 4 hit combo until you reach 250 hits.
It's relatively easy as I've done it twice to help friends do it, the only real challenge is mitigating the knockback your character will usually do after their combos

Here's a short video showing how I did it in Episode 5