Xander's Pokémon Adventure Challenge.
Yet Another Halloween Costume Challenge.
For Halloween Xander does not dress as a soldier.
After losing a bet to Dawn he has to dress as her favourite human Pokémon character!
Whilst Dawn dresses as her favourite Pokémon!
How will this change Sunnydale?!
I see this as going one of two ways either the normal Pokémon with Dawn stuck as her Pokémon or a Poke-girl version.
Maybe have Xander capture other people dressed as animals which we know there are some or have Xander capture the girls thinking they are feral Poke-girls