Every hero is a Unova Pokémon line. Fox is Snivy, Sir Oofie is Oshawott, Megachad is Tepig, and all 21 heroes have their own Pokémon, from Klink to Zorua to Axew. Level up mid-run and you evolve, cry and all.
Every enemy is a wild Unova Pokémon. Patrat, Joltik, Sandile, Frillish, Yamask and more, picked to fit each stage. Elites are shiny, minibosses are gym leaders' aces like Watchog and Excadrill, and the final boss is your version's legendary.
Weapons become moves. Flamethrower, Leaf Blade, Thunderbolt, Hurricane, Hyper Beam and more.
All sprites and cries are read from your own copy of Pokémon Black, White, Black 2 or White 2 (a DS ROM file you own). Melty asks you for it the first time you press Play. Nothing from Pokémon is included in the download.