Pokémon Duos
Caterpie and Weedle and their Evolutionary Lines.
Ekans and Sandshrew and their Evolutionary Lines.
Nidoran♂ and Nidoran♀ and their Evolutionary Lines.
Clefairy and Jigglypuff and their Evolutionary Lines.
Vulpix and Growlithe and their Evolutionary Lines.
Meowth and Mankey and their Evolutionary Lines.
Grimer and Koffing and their Evolutionary Lines.
Shellder and Staryu and their Evolutionary Lines.
Hitmonlee and Hitmonchan
Electabuzz and Magmar and their Evolutionary Lines.
Omanyte and Kabuto and their Evolutionary Lines.
Mewtwo and Mew
Murkrow and Misdreavus and their Evolutionary Lines.
Ledyba and Spinarak and their Evolutionary Lines.
Tauros and Miltank
Espeon and Umbreon
Steelix and Scizor
Teddiursa and Phanpy and their Evolutionary Lines.
Skarmory and Mantine
Lugia and Ho-oh
Silcoon and Cascoon and their next Evolution.
Lotad and Seedot and their Evolutionary Lines.
Sableye and Mawile
Ninjask and Shedinja
Plusle and Minun
Volbeat and Illumise
Zangoose and Seviper
Solrock and Lunatone
Huntail and Gorebyss
Latias and Latios
Gardevoir and Gallade
Cranidos and Shieldon and their Evolutionary Lines.
Stunky and Glameow and their Evolutionary Lines.
Bonsly and Mime Jr. and their Evolutionary Lines.
Leafeon and Glaceon
Cresselia and Darkrai
Phione and Manaphy
Throh and Sawk
Sewaddle and Venipede and their Evolutionary Lines.
Cottonee and Petilil and their Evolutionary Lines.
Gothita and Solosis and their Evolutionary Lines.
Karrablast and Shelmet and their Evolutionary Lines.
Braviary and Mandibuzz and their Evolutionary Lines.
Heatmor and Durant
Spritzee and Slurpuff and their Evolutionary Lines.
Tyrunt and Amaura and their Evolutionary Lines.
Pokémon Trios
Hitmonlee, Hitmonchan and Hitmontop
Vaporeon, Jolteon and Flareon
Articuno, Zapdos and Moltres
Entei, Raikou and Suicune
Regirock, Regice and Registeel
Groudon, Kyogre and Rayquaza (Trio Master)
Dialga, Palkia and Giratina
Uxie, Mesprit and Azelf
Zekrom, Reshiram and Kyurem
Tornadus, Thundurus and Landorus (Trio Master)
Xerneas, Yveltal and Zygarde (Trio Master)
Pokémon Quads
Articuno, Zapdos, Moltres and Lugia (Master)
Entei, Raikou, Suicune and Ho-Oh (Master)
Regirock, Regice, Registeel and Regigigas (Master)
Dialga, Palkia, Giratina and Arceus (Master)
Uxie, Mesprit, Azelf and Arceus (Master)
Virizion, Terakion, Keldeo and Cobalion (Master)
Note: This list may be incomplete so if you feel I missed any Pokémon out feel free to leave a comment.
Source for Pokémon Duos.
