I have a couple. My most notable ones are Wyrdeer and Gardevoir for strong style Hypnosis and Garchomp for False Swipe. Alpha Wyrdeer I caught as a Stantler in Obsidian Fieldlands, while alpha Gardevoir and Garchomp I caught as they are in Alabaster Icelands.
Nowadays I don't really feel the need to always have Hypnosis and False Swipe, since Sticky Globs do the trick, too, outside of battle. Still, they were nice to have back when I didn't know how to reliably catch aggressive Pokémon without starting a Pokémon battle. I've yet to catch a shiny alpha Pokémon-- those seem to be this game's rarest spawn, especially ones that aren't static alphas. I'm looking forward to the day I catch my first. :)