"Or maybe it should be the other way around - 1 pokemon = 6 items; 2 pokemons = 5 items... etc.

This would make casual battles more fair since different players may have less then 6 Pokemon in their party during more early parts in the game.... in a nutshell, it would be like a handicap in golf."

But usually when people have 1 Pokemon it is much higher level than someone with six because they have focused on training that one Pokemon. In Pokemon, when I only level my starting Pokemon it has already evolved by the second gym leader.

I like the idea of re playable quest, so you can go back and do it over, but couldn't Chef's Special  be replaced by a super potion or the food you buy at the restaurant, so going back would be discouraged except for experience. But it sounds fun.