Articuno, Zapdos, Moltres, Dragonite, Mewtwo, Mew, Raikou, Entei, Suicune, Tyranitar, Lugia, Ho-Oh, Celebi, Salamence, Metagross, Regirock, Regice, Registeel, Latias, Latios, Kyogre, Groudon, Rayquaza, Jirachi, Deoxys (all forms), Garchomp, Uxie, Mesprit, Azelf, Dialga, Palkia, Heatran, Regigigas, Giratina (both forms), Cresselia, Manaphy, Darkrai, Shaymin (both forms), and Arceus (all types).
This cutoff point may seem as arbitrary as any other and the number of banned Pokémon may seem very large, but in my experience it is the best way to maximize the number of viable Pokémon in the lower tier, thereby removing the need for an even lower, "UU" tier. I could count on both hands the number of fully-evolved Pokémon that I think are too weak to be used effectively in this Non-Legendary tier.