They way I was playing it, is that it beats any +4 or +5 or Booster Bru cards whether alive OR dead. But re-reading the card and I'm wondering whether it should be beat ANY dead card.
Please correct me if I'm wrong here:
The Upset card will autowin by 3 against any dead card
Where a 1 energy card played against a dead card would autowin by 1
In both cases the team bonuses are not used when your opponent plays a dead card.
I have been using this rule as a strategy when I have Hardy and I know my opponent has burned his good cards. I'll suffer a point of damage from his reaction attack so I can save my high energy card for my attack/tackle.