I wonder what the Pochika does...
Here's an explanation of Pochika from a member of another forum:
Rydia's battle-replacement summon Pochika (the marshmallow thing) has stats dependent on the number of times you successfully play minigames provided by the fat chocobo. The games vary in difficulty and goal, and which games are available depends on your current party members. An example is a stopwatch game performed with Rosa, where the player tries to hold the pen to the screen for a certain number of seconds while distracting music and sound effects go off in the background.
If you play the games obsessively enough, Pochika's stats fly through the roof, making him a pretty good automated fighter, mage, or healer. When summoned, his battle commands are randomly determined from a customizable list of every ability and spell which your current party's characters can perform.