>>38373518The three classes are Legendary 1, Legendary 2, and Mythical. Legendary 1 Pokémon are generally legal. Legendary 2 and Mythical are illegal. Mythical are not required to complete the Pokédex.
Legendary 1 is Articuno, Zapdos, Moltres, Raikou, Entei, Suicune, Regirock, Regice, Registeel, Latias, Latios, Uxie, Mesprit, Azelf, Heatran, Regigigas, Cresselia, Cobalion, Terrakion, Virizion, Tornadus, Thundurus, Landorus, Type: Null, Silvally, Nihilego, Buzzwole, Pheromosa, Xurkitree, Celesteela, Kartana, Guzzlord, Poipole, Naganadel, Stakataka, and Blacephalon.
Legendary 2 is Mewtwo, Lugia, Ho-Oh, Kyogre, Groudon, Rayquaza, Dialga, Palkia, Giratina, Reshiram, Zekrom, Kyurem, Xerneas, Yveltal, Zygarde, Cosmog, Cosmoem, Solgaleo, Lunala, and Necrozma.
Mythical is Mew, Celebi, Jirachi, Deoxys, Phione, Manaphy, Darkrai, Shaymin, Arceus, Victini, Keldeo, Meloetta, Genesect, Diancie, Hoopa, Volcaneon, Magearna, Marshadow, Zeraora, Meltan, and Melmetal.