>>52960454 I think the most in Yellow was for the last few gym leaders and the Elite 4. Koga's whole team has Toxic when they wouldn't normally otherwise, along with stuff like one of his Venonat having Double-Edge. Blaine has Flamethrower and Reflect on his Arcanine instead of Roar and Ember, and a Ninetales with Confuse Ray and Flamethrower. Giovanni also has a pretty good upgrade since most of his mons have Earthquake now, along with the Nidos getting Thunder. Lance similarly gets to load up his dragons with coverage on top of giving Aerodactyl a couple flying moves, rather than just spamming Hyper beam.
Prior to that though, early gym leaders didn't have as many changes or customization. Or at least not for the better. Surge has Mega Kick and Mega Punch on his Raichu, but he also lost his two other team members. Sabrina similarly traded out Mr. Mime and Venomoth for a single Abra with Flash and nothing else.
Gen 2 seemed to at least lean more into the gimmick of having Gym leaders make more use out of the TM they give you, like how Falkner's team all has Mud Slap, or Bugsy and Morty have Fury Cutter and Shadow ball on their respective aces. The problem there is that the moves themselves for most Gym leaders aren't very good. Still, I think that's where they started to get a proper grasp of how they wanted to handle movesets for important NPCs.
