For the jar game, unequip all attack abilities (since they add to your combos), and equip Negative Combo and the Fenrir, if you have them. Then just destroy as many little posts as possible. When a big pot shows up, aim it in to a group of little pots to get the max points.

What was your route for Poster Duty in Twilight Town? That's one of the ones I haven't gotten yet.