A Starter, Pseudo-Legendary, Legendary, Mythical, Ultra Beast, in the Eevee, Lucario, or Gardevoir line (Gallade is fine), or Pikachu specifically (Pichu and either Raichu form is allowed)? Different forms are included in that list, too, like Primal Kyogre, mega Mewtwo, the Galarian Legendary Birds or Iron Jugulis (Paradox Hydreigon).
My favorite is Unown! I really like the lore around them and their potential relation to Arceus. I also enjoy collecting the entire set of them. They are the Pokémon with the third most forms at 28 (the Latin alphabet as well as ? and !), after Spinda (ofc) and Alcremie, which has 64 different variants!
by Epicboss67