>>23502867I always thought getting to/ dealing with the sevii islands and unlocking cerulean cave on fire red and leaf green added a nice little bonus difficulty. Granted I was a bit younger when those games came out, but Imo those things alone make them more difficult than the other main games.
And unlike gen v and onward NO ONE IS YOUR FRIEND, NO ONE HEALS YOUR POKEMON FOR YOU. Caves are long as shit and you have to work to get legendaries and HMs.