Actually, if you go by the animated series, Walter beat The Mask several times, in fact, he punched him so hard that it broke in two. And afaik, The Hulk is quite stronger than Walter, though Walter is completely indestructible >_> And some variations of the Hulk have Bruce Banners intellect.
Mask is immortal and indestructable.
Hulk is not.
Mask is not immortal, heck if you judge by the comics, yes there are mask comics, heck the movie was kinda based on them, except the comics called him Big Head. And the only mask version that would have any chance against Hulk, would be Lobo Mask.
You just said “heck” twice. :>
The Mask can beat anything since he can become anything he wants and make anything he wants.