Battle Fa(g)tory managed a hilarious one on me.
Ojay, my opponent had a Froslass out against my CB Tyranitar. I use Crunch, it misses (I'm guessing Brightpowder here). It uses Hail. I switch out to my Kabutops, Blizzard, crit, it's dead. I switch Tyranitar back in and use Stone Edge. It misses. Frossy starts spamming Destiny Bond, and I eventually hit it and die from DB. Cradily (Toxicstall set) comes in against a Lapras who Quick Claw + Sheer Colds me. The last pokemon would have been a very easy Octillery.
156 Pokemon in the Unova dex. 6 of them are event Pokemon.
151 Pokemon in the Kanto dex. 1 of them is an event Pokemon.
When you see it...