Abadede is no joke on most any difficulty; he hits fast and hard, can break out of combos and grabs and has high damaging uppercuts and suplexes that can really put a hurt on you. This doesn't have to be done without dying so just merely get past him. Try not to stay too far away for any extended period of time (his charge is deadly), and attack when he's left himself open after a missed lunge. Alternately, if you're series vet, a good tactic is to keep your distance and let him run at you, then jump kick him. Now back off, rinse and repeat.
Here's a few points to remember:
Don't try and throw him at any time. He'll always grab you first, and his suplex is extremely painful. Try to look for moments where he's distracted doing something else, like missing an attack.
If you're feeling lucky, most every attack except for his grab and lunge can be stopped with a perfectly timed jump kick. It's not something to lean on, but it's great for stopping him in his tracks.
If you're going Single Player, save often, and don't take unnecessary risks. This is not a boss to trifle with.