>>41892086There's a fangame that comes up a lot here called Pokemon Reborn. It's got a shitty story but it introduces an insanely fun mechanic based on anime battles:
Every gym leader battle has a "field effect", usually similar to the terrain moves, which usually benefits the gym leader's pokemon, but can also be turned against them.
For example, the grass gym leader has a grassy terrain like field affect which absorbs water, reduces the power of earthquake and boosts grass type moves. But you can set the field on fire with a fire type move and negate all the positive effects it has on the gym leader's team.