The mod creator calls this a ‘Buddy Pet Mod’ but this is definitely a minecraft Mini-me mod. The mod creates a small version of you – a mini-you to run around in your minecraft game with you. Your mini-me spawns when you do, logs off when you do and runs about the world much the same as you do. If you don’t want to lose your mini-me, you can right click to wear him or her on your head. It makes total sense.
If you don’t want to run around with a miniature version of yourself, but do want a pet, you can change what your mini-me looks like. This is where the pet buddy part of the mod comes in. It is possible to have your mini-me incarnate as any minecraft mob. So you can have a minecraft pet spider, pet pig, pet skeleton, pet enderman, pet bat, pet villager or pet (insert minecraft mob name here).