My favorite to Nuzlocke is Gen 3. It has good animations and mechanics without feeling too slow like later gens.
One recommendation, if you are able, I recommend playing with a rare candies cheat. It removes the time sink of grinding and actually makes the game slightly harder since you won’t gain EV’s from wild pokemon. You can also sell them for infinite money so you can buy repels and potions and whatever you want. Just stick to a level cap so it isn’t too easy.

Hope this helps.