The LJ-cut will take a little while to fully load (due to the three videos), but trust me, it's well worth it. ::giggle::
The descriptions are excerpted from the Chocobo Mode thread (by X-Soldier) at the Advent Children Crisis Core Forums (just follow the instructions to access the Spoiler Forum).
Moogle - Moogle descends from above, Zack is pleading for help from the moogle. The moogle takes all of your materia and combines it into one. May also level up all materia.
Cait Sith - Runs and bounces around Zack in a circle, before clapping, in front of his face, sending stars spinning around him, as he leans back, and spreads his arms apart, face tilted lightly skyward. Cait Sith then comes close up to the bottom right of the screen, and waves at the player as it exits back to the regular battle screen. (Status affect similar to Shizune (Cissnei)'s Lucky Star - Temp invulnerability).
Magic Pot - Magic Pot is shown at the beginning, and the little demon or whatever pops out and did some actions, then Zack comes over and ransacks the interior of the pot to get an item. Zack then gives the thumbs up pose, smiling with a tinkle at the corner of his smile and stands up, raises his right arm into a fist motion. The item is a gold bar that can be sold for for 50000 gil.