The Koopa Bros. have nothing on the real Teenage Mutant Ninja Turtles, but this work, along with a parody video by James Farr, are among the best to mash the two together. Purple Koopa managed to hold on to his front shell, whereas most Koopas who lose their shells pop out wearing only undershirts, underpants, or both (as seen in Super Mario World and Yoshi's Island).
All that is needed is to add Don Churuge/Mouser, Princess Daisy, Luigi, and Professor Oya Ma/Elvin Gadd as Master Splinter, April O'Neal, Casey Jones, and Baxter Stockman respectively.