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Side-scrolling shmup with Vikavolt.
Enemies would be all sorts of flyers like divebombing Talonflames, tracking Dreepys, exploding Drifblims, rows of Magnemite and Beedrill. Minibosses like bullet hell Dragapult, zipping Garchomp, Magnezone with orbiting Magnemite shields. Bosses like Lati duo, Celesteela, flying form Genesects, Mega Fug, etc.
If it has walls like Gradius you can add all sorts of non-flyers. Or you can do low altitude levels, like a river with fish mons jumping out of the water, and a Gyarados boss.
Weapons and powerups naturally themed after moves and/or small support Pokemon.