I have a question about how to add new status effects that can be inflicted on the player to the game, as I think there is lots of potential there when it comes to unique enemy designs.

I did find most things I needed in the sprites, enemy jsons and player.json file, but where is the information stored on what a status effect actually does? Like, if I get hit by a projectile, and the game is told that on-hit, the character is inflicted with "Plushie", how does the game know on what the player can and can't do during that form?

Status effects are hardcoded within Ghosts & Japes, and there is currently no way to add your own.

This will not be the case in some other projects, and may eventually change in this game as well.