If they did him right, than he has some kind of adaptation to the opponent.
Doomsdays trait should be 10 seconds or something like that of heavily, heavily, heavily reduced damage, if the opponents does the same shit over and over again.
Let's say Doomsday VS Green Arrow, both are low health and Green Arrow wants to chip Doomsday out from the distance. Doomsday would turn on his trait and be able to take the first arrows, but the following ones wouldn't do any damage at all, because he adapted to them.
Same for other stuff ... durnig his trait you wouldn't be able to combo him with an easy combo like 1, 1, 2 because the first 1 would deal damage, but the second 1 wouldn't do any damage at all and the following 2 would be the damage dealing hit again.
So either you would have to do normal attacks to do damage on him, or do your regular combos, but without any real damage - you would basically only do it to waste the time of his trait, or you would have to play defensivly, or what the hell do I know D:
Other than that Doomsday could have a lot of shit.
I would like to see some huge ass leaps, him hitting the ground and creating huge earth-shattering earthquakes and so on. No grappeling, but pure god damn power.