I guess if defines what you call your "best". I have a Rhydon that knows all 100+ power moves, My start, Blastoise, Raichu and some others I picked up from the wild. If you get anything rare in the wild that someone else may want, you can get better pokemon through trading (Note you must be level 10 though)
My philosophy in the Pokémon games is to just use the best Pokémon I come across on my journey. In Pokémon Y, I took on the Elite Four (successfully) with a team that included Talonflame, Charizard, and Pidgeot, and my starter Chesnaut. Obviously no "Dream Team" but it got the job done. The main thing is getting a decent range of types (not three flying types like I did) and high levels and EVs. Of course this is my opinion.
I usually like to play with my favorite pokemon. Well my favorite pokemon are the strongest. I suggest adding: Dragonite Snorlax Gengar/Alakazam on your team at least
