I go with Zoro, Oden, Ryuma. Ryuma was said to be on equal terms Joyboy and I believe Joyboy in prime could've defeated Imu (WE DON'T KNOW IMU'S POWER SO PLEASE DONT FLAME ME). I then think Oden and Zoro would overpower Luffy. Luffy's only weakness is swords so that is horrible for him. He might win a fight against them but if Ryuma win's the fight against Joyboy (Its like a 50 50) then Ryuma will just come over to Oden and Zoro and just solo him. Yonko's are just nothing to Ryuma to. GG.