My pet has purple/black weird textures

This is an issue with your Model Engine resource pack. The textures are either missing or not where they are supposed to be.

Reload ModelEngine with "/meg reload". Fetch the resource pack into "./plugins/ModelEngine/", there is a "resource pack.zip". Take that file, put it into your "resource pack" folder in Minecraft (Escape menu, video settings, resource pack, then open resource pack folder).