Sylveon- SS tier
Obtainability- Starter
Main ability-Pixelate
Moves: Skill swap, Hyper Voice, Draining kiss, quick attack (for the early game, after you can sub it with whatever you want)
After spending days resetting for my eevee, i knew it was worth it when i got sylveon. Sylveon s*** on every shadow pokemon, stab draining kiss one hit ko's nearly all of them with the added benefit of healing back 75% of the damage dealt. Even though Sylveon isn't a physical type attacker, stab pixelate boosted quick attack hurts alot. Does massive damage at the early stage, and is good because it can pick off weakend fast yet strong boss pokemon you may encounter. Without a doubt the best move for the game, skill swap. Remember that huge power medicham? Skill swap with it and its attacks do basically nothing while you just gave Sylveon pure power which makes Medichamp no longer a threat, and boosts Sylveons quick attack with huge power. After skill swapping, you can just spam quick attack and you just destroy everything. Remember that pesky volcanion? Skill swap with it and you get water absorb, so its water pulse spam just heals your sylveon further and you can then proceed to kill it with whichever move of your choice. Another positive of Sylveon that needs to be reiterated is the fact that shadow Pokemon mean nothing to it. I remember watching people play Rejuvination, and they would rq because since Shadow moves are super effective against everything but fairy, they would KO all their Pokemon instantly. Sylveon just walls all of them.
All of this coupled witht he fact that Sylveon has great attacking and support capabilities, it should be SS.