Assuming it's not underwater,Kl'rt wins easily. Namor is tough as nails but the Super Skrull takes him out. Namor can only do physical damage and Kl'rt has 3 defenses for that. Between the Thing's tough hide, Reed's elastic body and Sue's force fields, Namor will have a tough time causing any real damage. With the combined powers of the F.F.(albeit to a lesser degree) the Super Skrull has many ways to outmatch Namor. Underwater gets a bit closer, probably a draw.
Although Klr't has the powers of FF Namor still wins....I want to say, ut truth is Invisible woman can beat almost anyone by creating an anuerysm by generating a small forcefield in hr opponents Braind or heartattack with the same method, and so on.