Os dejo una lista que acabo de hacer con los legendarios que no se pueden conseguir en X/Y y las formas que me se de conseguirlos.
Saludos
#151-Mew: Esmeralda (evento)
#243-Raikou: HeartGold/SoulSilver
#244-Entei: HeartGold/SoulSilver
#245-Suicune: HeartGold/SoulSilver
#249-Lugia: HeartGold/SoulSilver, dream radar (con pomemon SS)
#250-Ho-oh: HeartGold/SoulSilver, dream radar (con pokemon HG)
#251-Celebi: Evento GBA
#377-Regirock: B2/W2
#378-Regice: B2/W2
#379-Recisteel: B2/W2
#380-Latias: Blanco 2
#381-Latios: Negro 2
#382-Kyogre: HeartGold
#383-Gourdon: SoulSilver
#384-Rayquaza: HeartGold/SoulSilver
#385-Jirachi: Pokemon Chanel+Gen3
#386-Deoxys: Esmeralda/Verde/Rojo (evento)
#480-Uxie: B/W, B2/W2, P/D/Pt
#481-Mesprit: B/W, B2/W2, P/D/Pt
#482-Azelf: B/W, B2/W2, P/D/Pt
#483-Dialga: B/W, B2/W2, P/D/Pt
#484-Palkia: P/D/Pt, dream radar (con pomemon D)
#485-Heatran: B2/W2, P/D/Pt, dream radar (con pomemon P)
#486-Regigias: B2/W2, P/D/Pt
#487-Giratina: P/D/Pt (evento), dream radar (con pomemon Pt)
#488-Cresselia:P/D/Pt, B2/W2
#489-Phione: Criar Manaphy
#490-Manaphy: Ranger+P/D
#491-Darkrai: P/D/Pt
#492-Shaymin: P/D/Pt
#493-Arceus: P/D/Pt,
#494-Victini: B/W (evento)
#638-Cobalion: B/W, B2/W2
#639-Terrakion: B/W, B2/W2
#640-Virizion: B/W, B2/W2
#641-Tornadus: B/W, B2/W
#642-Thurundus: B/W, B2/W
#643-Reshiram: B, W2
#644-Zekrom: W, B2
#645-Landorus: B/W
#646-Kyurem: B/W, B2/W2
#647-Keldeo: B/W (evento)
#648-Meloetta: B/W (evento)
#649-Genesect: B/W (evento)