I got it from the Reddit guide, it's Shiki with a friend Legend BB, along with Raid Doffy, Raid Boa, Raid Sabo, and Colo Kid (Kid can be replaced by Diamante or Barto). Against Cora you just use BB, Boa and Sabo on turn one, which will let you get rid of most/all of the other enemies (BB negates the shields, and Sabo/Boa lets you do high damage even with Greats). After Cora gives you bombs on turn 2, you use Shiki and Doffy and focus on Cora (Sabo and Boa will still be active). If there's still any enemies left after that you can take them out on turn 3.
As for stalling, I took out all but one enemy on Wave 1 and single-hit him with Boa or Sabo for as long as possible. Wave 2 has a Giant, who does a lot of damage, and Bodyguards, who will delay your STR specials after the second turn (VERY BAD), so you can only really get 2 turns here. Stall on Wave 3 much the same way as Wave 1. Wave 4 you can let the Pirates fail to lock you on their first attack, then leave one alive along with the turtle and stall there. You have enough HP between BB and Shiki that you can get around 32-35 turns if you wait as long as possible. You shouldn't have to take any hits on Cora so you can use as much HP as you can along the way. Autoheal helps, of course.