Well... with this data looks like only way to get it is through home.

Hmmm... given to you maybe but whom?
but the encounter would be saying that there is away to.

So maybe future event.

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Oh yeah you have to do the galarian star tournaments in a row without any Pokémon fainting

Just try it a YouTuber named adrive said that

Victini if I recall correctly is the "Victory Star" pokemon, which would be why it fits with the galarian star tournament. I've beaten the tournament with everyone available and can confirm that you don't get them that way. I have two from B&W and there is no pokedex entry for them.

I know how to do the galarian star tournament 73 times then shake the big red tree 800 times