Composite Kratos, on top of having access to all feats and powers in his games, would also be the God of War and as such be like over a hundred feet tall or some such shit.
Though it doesn't matter. Kratos would rip Thanos' arms out of their sockets. He's physically much more formidable as well as quicker.
Well, a composite Kratos would definitely win the first scenario, at least.
Not sure about the second, but Kratos would need to stay away from a contest of raw power(since Thanos has infinite power), and try to decapitate him while blitzing him or something.
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