I recall at SCR King Hippo fought Whiteboi in top 8 and lost but Hippo claimed he had almost no Doomsday experience so you can't really go by that. I honestly think this match up is 5-5. Deathstroke can keep him in check with low shots and when Doomsday has meter I tend to bait out the shoulder charge to make him waste it. If there's one thing I've noticed about most Doomsday players is they don't like to be pressured and are not the greatest at blocking. Try baiting out his wakeup attacks since none are safe and the only invincible one he has is the upward venom which isn't safe. Oh and of course being able to block earth shaker successfully can really take away the momentum from him.