>>44702456lmao, you can do all of that and the games are still easy. My last sapphire run I went trough 40 pokemon just to keep myself 15+ levels under my enemies and used all sorts of shitmons like magcargo, linoone and mightyena. I even had all my pokemon learn HMs like cut and rocksmash to keep their movesets garbage and it doesn't make that much of a difference either.
Team rotation is just a meme idiots on /vp/ parrot every time someone mentions difficulty. As far as challenge goes it's barely anything at all. It just changes battles from "pick the move that kills the enemy instantly" to "set up or debuff the enemy and then 2 or 3 shot their pokemon to death".