None of these characters are in the same rpoc plots (except meme and momo) The mini minion is just happy as usual, but the zombie doll is confused on who the others are.

Meme & Momo are Vincent's.
They are summoned from being pulled out of his hat.

Zombie Doll is Jigoku Jr's.
It was created by scientists ,and... stuff. Long story short ,it's her's now.

Black Parade Mini Minion
Tumer's first level of minion. Their reason is to eat to help fuel their master and the other minions. They other minions can not eat for themselves (or at least only the 2nd level).