The most consistent way to gain experience points (EXP) is by battling NPCs.
A full 7-trainer run through the Trainer Tower will take roughly 5 minutes and will boost a Pokémon from Level 1 to Level 85 instantly. Two runs = Level 100. pokemon vortex level 100 training free
: By choosing opponents whose types are ineffective against your Pokémon (e.g., using a Ghost-type against a Normal-type training team), you can win battles repeatedly without taking damage. The most consistent way to gain experience points
So put on a podcast, turn off your brain, and go beat up Misty for the 400th time. Your Level 100 Shiny Mewtwo is waiting. turn off your brain