i would imagine so, but ive never tried it. to create this situation you would probably have to make a double battle and put both foes to sleep before trying to kill some of your own guys. maybe two smeargles with spore - one with belly drum and false swipe (and focus band), the other with counter. put both foes to sleep, use belly drum next turn. the turn after that use false swipe and counter. it might take 10-20 tries before the focus band activates. and even if it doesnt, it still doesnt prove that it wouldnt work.
one thing i do know, is that focus band can allow you to survive a OHKO move. i know because it happened to me in the battle factory. my wobbuffet was in and the opponent used a OHKO move which hit (of course) and as i was watching the HP slowly drain away i was thinking first "why do their OHKO moves always hit?" and then "it would serve it right if focus band activated here" and then "hahahahahahahahahahahaha
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