Gragas is fairly high maintenance as a champion as he's almost useless if you can't land his skills and you don't have the cd nor mana to spam them until late game, but he's not very item dependant early or mid game, and late game you can be fairly under farmed and still hold your own.
But once you get used to him, he can play a mean caster, or a pretty annoying tank. Land that q and their physical carry just lost all their thunder. And screw them up with the ult and a team fight of 5v5 can degrade into a team fight of 5v2 or 5v3 very quickly.
Haven't seen this Shushei guy play, but it sounds like he knows what he's doing. He plays AD tank gragas, AP tank gragas, or some sort of hybrid?
And Malz shouldn't get nerfed :< I love him for his burst carry raping. And his burst tank raping, but that requires a feed :3