Doomsday has beaten Darkseid to a pulp with nothing but brute force. Can he do the same to Thanos?
Doomsday is strong and powerful enough to beat Darkseid in hand-to-hand combat (as I said), he is almost invulnerable to physical and mental damage and he can move to fast for the entire Justice League to handle.
Thanos is so strong he has destroyed planets with the force of his blows, he has withstood attacks from Thor and Silver Surfer without getting injured, and thanks to his immense strength and advanced musculature he has superhuman speed, agility and limitless stamina.
Who takes this? Also, remember that Thanos also uses intelligence at range in battle, and his mind is possibly his most dangerous weapon.
They can use any of their powers to their advantage, but keep it unarmed combat.