Skill is debatable. Kratos has years upon years of training and became the greatest general of the Spartan army, and that was before he attained godhood. Kratos may not study the same martial arts as Goku, but he has very extensive combat training. If you watch any of his fights, he is very crafty and has a tendency to evade attacks of more powerful opponents as well as snatching weapons from them before using their own weapons against them.
I'm fairly certain in an arm-wrestle, none of the characters below Beerus tier would be able to beat him. Zamasu arc and ToP is where it goes up in the air on who's stronger.