Board Thread:Questions and Answers/@comment-33220088-20171001043837/@comment-33728484-20171001092900

Buuhan doesn't get any boost from the leader skills, which means that he hurts your team as a whole (HP is very important, especially when it comes to Boss Rush). You could use SSJ4 Vegeta, who's one of your best cards (even though he isn't dokkan awakened yet), a defender like Piccolo, a strong INT unit like SSB Vegeta, or Whis from the Evil Powers Strike Back event (stage 20) if you want to bring a healer.

But first you should dokkan awaken as many characters as you can before going into such a difficult event (at least those whose events can be found in Boss Rush), because they all get a lot better.