Currently, I'm trying to be as cheap as I can think to be in rival smash: using characters like Bowser and Zelda to keep the rival in the air as much as possible, while taking advantage of their decent offensive capabilities. The most I can seem to get is 20, but Challenge Board 3 has a requirement of 50 kills.
I understand that there is a decent amount of skill required to complete this, but I'm sure there are some characters who naturally do better than others. Is this true, and if so, which characters work well for this encounter?