Conqueror of the Violet Gym
It was alright in gen 1 as you could just buy all of the stones bar the Moon Stone, and there's enough Moon Stones for all 4 evolutions. Gen 2 is where it got bad, and then gen 4 added a load of single use evolution items. It wouldn't be as bad if they didn't disappear after use. At least Sword and Shield has regenerating stones in the Lake of Outrage but before that game you're shit out of luck. Especially when the item for a trade evolution is postgame locked behind a fucking battle facility.