Evolution based on location. Easy to make thematic and narrative driven:
>Magnet Pokemon attracted to electrical impulses in the air
>Dangerous where a fighting mon must prove itself as a right of passage
>Pokemon that loves technology in a room of supercomputers
>Mon meets with an elder dragon that bestows its power onto the mon, evolving it into a full-fledged dragon-type
>Haunted area where the pokemon gets posessed by a ghost
>Chemical zone mutates pokemon
>Trainer and mon must traverse Ancient Ruins on their own. At the end of their journey, a spirit entraped by the ruins teaches the pokemon a signature move and evolves it
