Shout-outs to the lv99 Scatterbug I received once; that's dedication to trolling. The shiny lv100 male Snorunt was a hoot, too.
Other honourable mentions go to GROUDON? the Kakuna, Brad Pitt the Larvitar and Sorry the Bunnelby. I felt really bad for Sorry so I'm training him up for my Pickup team ^^
I've gotten a lot of cool stuff, like weird egg moves and RNG'd legendaries from last gen and stuff, but possibly the coolest was a lv 5, well-bred, Hidden Power Fire, EV'd Smoochum.. someone out there plays Little Cup <3