Gym rematches. Maybe with old pokemon. The first gym would be a triple battle, with the three monkeys and the starters.
Have pokemon naturally do hms.
A fire pokemon would have flames for light in a cave.
Any cutting move (leafblade, nightslash) could cut trees and theyd never grow back.
Or atleast forgetable so it can be
*teaches emboar strength*
*moves boulder*
*teaches emboar wildbolt again*
Nursey: holds up to 6 eggs, one pokemon (magmortar, camperupt, etc).
Again kyruremu needs 2 formes. Coldflare form is ice/fir, Freezebolt is ice/elc.
Major plotlines for every legend. As in big 3 day mission. I want the musketeer trio to be roaming for a bit. Meet them in route 1 but are protected. Appear to attack plasma a few times, and end up helping you.
Seven sages need pokemon to fight with.
Dive needs to last forever. Have some scuba diver trainers, tons of ruins, a few hidden islands, a place like the underground.