This is a disassembly (+ some added features) of sprites 4-7, the normal Koopas, and DA-DF, the Shells (normal and Disco variant). It includes a lot of options that can be set either with the extra bytes or with the defines (check out the asm files for more info).
It's included a json file for each Koopa color that will set up a list of sprites in LM's menu with all the main variants (Koopa, stationary Shell with or without a Koopa inside, kicked Shell, Disco Shell).
One of the most common enemies in the Mario worlds never as a custom sprite so having customisable Koopas are always so nice.
Be aware that if you carry them to a different level, they lose their custom status and revert to their vanilla counterparts. Keep also in mind that coin blocks which have been triggered by shells offscreen still display their coins.