How do you get Meeseeks box in Pocket Mortys?

Found in item boxes in all dimensions, as a reward from trainer battles, and in bundles purchased from Blips and Chitz. Instantly defeats another Morty.

What does Mr Meeseeks box do?

A Mr. Meeseeks Box is an item in the game Pocket Mortys. It can be used in battle to instantly defeat another Morty.