Boss battle with PK Idea:

He takes a form representing an element and is only willing to use attacks related to said element until the form's defeated (HP turns to 0).

He never starts out with the None element.

He also looks different depending on the form, and has all the abilities that'll prove advantageous with a one-man party who's only willing to use one element.

When HP drops to 0, he heals all the battlers in the arena (including himself) in both HP and MP, restocks all the PC's ammo/uses/etc. (when there's PCs with ammo-based or limited use {but rechargeable} weapons), and resets all the one-time-per-battle abilities (since each form counts as seperate battles), and then changes form to the one that's not the one he's already used nor the None element.

When PK manages to cycle though all the possible elements, he'll then take up the None element and then do random powerful attacks from any element.

In case you're wondering, PK has a effective level of over 25, so he doesn't get confused when he take upon the Pizza element.

Also, in character, PK has the ability to speak all languages, so even if he's not in Squirrel form when taking upon the Squirrel element, he could still speak Squirrel.

If you're wondering how PK could know all these moves, PK is a mimicker who's billions and billions of years older than what scientists who believe in the Big Bang claim how old the universe is.

Not only that, he's a "literal researcher of anything", so PK knows enough attacks to be considered a demigod.