Well no, this is simply untrue. He has a vast majority of weapons and fighting styles, which in my opinion he uses very well. He's also basically killed the equivelant of a bunch of gods, demigods, demons, etc. He's also half of a fiend from what I remember. Also "wall running" isn't the only skill he has. He can also teleport and do much much more than just wield a "magic katana".
Going by default weapon, in his case, Dragon sword.
I'm not trying to downplay him, I'm just trying to point out that he actually falls kind of short compared to other action game heroes.
For example. When he wields the chained flails, he just does regular nunchuk moves with them, nothing special. Whereas Ken Ogawa uses his to not only do that, but tow a hugecargo airliner jet to a halt with his bare hands as well as deflecting projectiles.
Ryus teleports are fairly basic (his magic wind away at the end of NG notwithstanding seriously wtf was that).
But against Kratos...like I said, Ryus main challenge is he is ridiculously squishy, getting killed as easily as a regular person would if he's actually hit. And Kratos is a super powered berserker.
So the only way for Ryu to win is to assume he'd never get touched by Kratos, but that'd be kinda Mary Sueish.
On Kratos end, id say he has a lot more durability than Ryu, plus more range with his attacks and is also a literal Godkiller.
Also in NG demons and such are apparently just normal monsters with long lifespans, except maybe Doku.
Ryu does fine but I don't really think he stands a chance against others like Kratos, Dante, Ken, Raiden, Asura, etc.
Also yes Raiden does blow ryu totally out of the water, in terms of speed and power. Actually in terms of speed and power I think raidwn beats everyone. Except maybe Ken matches him in strength.