Okay. So, one day I was battling in the Battle Subway in Black.(double battle) Opponent's Floatzel & Shuckle vs. My Serperior & Magmortar. When Serperior used Giga Drain on Floatzel, Floatzel's Focus Band activated. What in the world? I thought BS Floatzel's couldn't have Focus Bands. On my next turn, I used Giga Drain again. (On Floatzel) Its health stayed the same for 15 turns even though I kept hitting it with Giga Drain.
Edit. My sources prove that none of the bs floatzels can have a focus band. So It was a glitch.