I didn't make these up, but I had them used on me in Random Matchup, lol. They're VERY gimmicky, but if you can't play around the tactics, you're likely to find yourself screwed:
First one I saw was a lead with Starmie and a Swoobat. What I didn't see coming was that Starmie used Skill Swap on Swoobat and got simple. Swoobat used Tailwind to set up speed for its partners, then Starmie unleashes a Minimize and tries to get some Cosmic Powers in. I don't know the full set for the Starmie because I managed to taunt it 3 for 3 times despite +4 Evasion, but seeing as it struggled every time, my guess is that it probably had Toxic and some other support move. Not the most awesome tactic in the world when I look back on it, but it was something that you would NOT have had your guard up for. And YES, I do know Simple Swoobat isn't legal for VGC 2012. Possibly in '13 maybe? I dunno.
Next one is another one I faced on Random Matchup like, 30 minutes ago, lol. Person leads with a Spinda and a Latias. Person has Latias use Skill Swap on DW Spinda to gain Contrary. You already know where this is headed, don't you? A +2, +4, and a +6 Draco Meteor is something fearsome, especially from a Latias. However, the tactic was still beatable, and had to rely on support from using Protect and switching to Togekiss to sponge some attacks Latias would have been smashed by with Follow Me.
...Lol, I still lost due to a low damage roll on Togekiss, but these gimmicks are pretty annoying at best. I could probably bring a few original ones I thought up myself, but I think this'll do for now, lol. I like seeing the weird, interesting things that happen on Wi-Fi sometimes. Although I hate being the victim