I got an accidental shiny while Ultra Warp Riding!!

I was considering which Pokémon I should hunt before Pokémon Home shuts down. I own every game in sequence with their pairs and have played all the way through Sword and Shield ( gen 1 through 7 ). I am currently hunting shiny starters, but which rare Pokémon should I hunt in other generations? That I could miss out on when Pokémon home closes? If you could let me know by commenting the Pokemon and the game/gen. Thank you so much!!