Um, well I tried this in a two on two battle using Wobbuffet and Nuzleaf in Pokemon Ruby. I never looked into seeing if a single pokemon could learn them both. Ideally this would be the moveset I would make with that stratagy...
Encore, Torment, Meanlook/block. Counter/etc.
of course no one said you had to do it on just one poke. You could just Torment first then baton pass to a Wobbuffet. (Off the th top of my head I think Umberon can learn Torment and Baton pass not sure on this.) Wobbuffet's shadow tag takes care of using Mean look and it can learn Encore as a Wynut.
I belive there is an Item or ability that a poke has that makes moves like furyswipes, double slap, etc. last longer. If the poke that encores has this item/ability i THINK it would make encore last longer. also, I'm not sure if the rounds spent using Struggle count towards the count of Encores... Off the top of mey had I think they don't beacuse techniclly the player didn't use the same move. But that stuff tends to fall into a battle rules gray area.