User blog comment:Ghurles/Team Help for Arena and Trial 1/@comment-25421406-20141110181510

For arena you want a rainbow squad with heavy ATK units, an ATK boosting lead (I would use Tiara- she has a great lead for arena), and the 2/3-turn ATK spheres (30% boosters from chronicles also work)

ATK teams almost never lose, easily taking out 1 or 2 units on the first turn which drops plenty of BBX.

Choosing units with low cost AoE BB's works, but not very dependable.