This was hilarious, even by TBBT's high standards. The whole Justice League setup worked brilliantly, from the guys bullying Zack and then realising they needed him, to Penny reluctantly becoming Wonder Woman. The costume rivalry gave everyone something funny to do, and the running jokes kept landing.
I particularly loved the group's attempts to apologise to Zack after treating him like an idiot. He may not be the brightest guy in the room, but his easygoing nature makes him a surprisingly good addition to the gang.
Penny in the Wonder Woman costume was another highlight, and the final reveal of all the Justice League teams competing for the prize was a great payoff.
And then there's Sheldon, preparing his grand acceptance speech only to have the countdown steal his moment. That was pure Sheldon, and I was laughing at how personally he took it.
8.5/10: Almost every gag landed, making this one of the season's strongest episodes so far.