18 Vivillon Region-Based Forms, 2 Event Forms: GTS Helpful Guide
/Now with Pokémon HOME being out, you might be able to do trades over the GTS that seems more difficult back during the Pokémon X and Pokémon Y era. Vivillon was introduced in Generation 6 and encouraged GTS and Wonder Trades. Vivillon’s forms were decided through the region originally set on the 3DS, so trading is your best way to collect them all.
If you want to keep track of your Vivillon, I made a helpful graphic to track your butterfly trades.
I've started a new goal of trying to get all the Vivillon forms passively on the GTS!
— It’s Super Effective (@pkmncast) August 21, 2020
There are 18 forms that are region specific and 2 forms from events.
If you are looking to complete the #PokemonHOME challenge, wanting to collect, or just curious about Vivillon, here you go! pic.twitter.com/5RcQeBOW64
Can you take a Vivillon pattern through trade and breed it for more? No, you cannot. Breeding different forms does not change what your game sets when you start your Pokémon X/Y journey. Can I change my 3DS region to get more forms? Technically, yes … but … you must change your DS region, then restart your copy of Pokémon X/Y for it to register the new pattern to that game.
If you have any questions, let me know!