User blog comment:Masterpolygon/Future Card Buddyfight: Aim for it! Buddy Champion!! Info and stuff/@comment-25240585-20170331005937/@comment-11215998-20170403140010

I'll let you know about 15 later (Because I can't remember the solution, I've done it before though.)

Challange 14:

Set Judgement and use it's effect, call Headhunt Jailer, Sai to the Left, Right, and Center. Call Gagalgarios to the center over Sai. Attack with everyone. Final Phase, impact call Gagalgarios, "Demonic Pyre Wave!" to the right over Sai and destroy Judgement for the call cost, for the size check, SEND THE LEFT SAI FIRST, you will still be over the size limit, send Gagalgarios in the center to the drop zone. You will now be at exactly 20 cards in the drop zone, allowing Demonic Pyre Wave to activate it's ability and the damage from Life Link and his attack should be game.