Xatu... I've been able to successfully use a Xatu in both the OU and Uber metagame, so he doesn't suck as badly as some people would think. His main gimmick is to switch into Close Combat/Earthquake, hit with parafusion, and Night Shade the cripple or its replacement. I've also been told that I look like a Xatu, since I have a tendency to stare off into the distance in the middle of a conversation. By the way, Xatu is a totem condor. A lot of people don't know that. In fact, I remember someone calling him a parrot...
Dusknoir... I've always been a defensive player, and Dusknoir is my most recent tank (replacing Umbreon). Multiple type immunities, base 135 (?) defenses, and is capable of dealing decent damage with Pain Split, a trait that Umbreon lacks. Plus, Will-O-Wisp is one of my favorite attacks.
Gliscor... looks like a robotic enemy from the early Sonic games, which is probably the main reason I like it. Seriously. Battle-wise, it's remarkably easy to Swords Dance once and proceed to sweep an entire team (assuming you're using Timid + 252 speed, anything else is too slow). Expert Belt is godly on him, as the elemental Fangs give him broad coverage. He's also able to fill roles as a Spiker, P-hazer, wall, and Baton Passer. He's a pretty versatile... whatever the hell he is.