>>55166350Either play Pokemon GO can catch them in that game as a special research reward, or wait until their next distribution. Some of them, you can catch in previous games for an unlimited amount of time.
Mew - NPC in BDSP if you have LGPE save data, or in LGPE via the Pokeball Plus
Celebi - If you have the 3DS Virtual Console version of Crystal, you can do the GS Ball event
Jirachi - NPC in BDSP if you have SwSh save data, or via the Colosseum bonus disc
Deoxys - ORAS
Manaphy - PLA, or trade over the egg from Pokemon Ranger
Phione - PLA, or breeding Manaphy
Darkrai - PLA, if you have BDSP save data
Shaymin - PLA, if you have SwSh save data
Arceus - PLA, or in BDSP if you have PLA save data
Victini - Inject a Liberty Pass into a gen 5 game, otherwise not available outside of events.
Keldeo - SwSh Crown Tundra DLC
Meloetta - SV Indigo Disk DLC
Magearna - Scan a QR code in a gen 7 game (Pokeball form is available as a gift if you complete the HOME Pokedex but that requires a regular Magearna first and all the other mythicals)
Meltan - Unlimited supply in Pokemon GO
Melmetal - Evolve Meltan in GO, or recieve a G-Max one as a gift when you transfer from GO to HOME
