AP and Dura: The bear, but not by much. Valev downscales from a 6-A to the border of High 6-B, and it seems the bear is calcless, regardless.
Intelligence and Skill: Valev, by a tremendous amount. Valev's tendency to be a bit light-hearted may hurt him, but if the tides turn bad, he'll certainly turn serious and regain any lost advantage.
Range: Big Bear, although with their given speeds it really isn't going to matter that much.
I'm going to assume Speed Equal, even though I don't believe it was specified. Although, Valev can amp insanely high, too.
With 5 second prep time, Valev probably just durdles around and talks to some clones for a moment.
Absorption is the biggest hurdle for Valev to pass, but not one he can't defeat. Valev's Anamnesis would help him deal with being absorbed if the bear can absorb melee attacks, and Valev does have one spell that combusts and does massive damage when absorbed (There were a lot of users who absorbed attacks, especially fire, in the World of Myths rp).
The second thing Valev has to overcome is the bear's One-Hit Kill, which sadly won't be that useful here. It needs to charge, which is basically a death sentence against it's usefulness. Valev is far, far too mobile for something like that to hit him, and his speed amp will make the gap in speed quite large.
Valev's nails in the holes; time stop, and clones. The clones allow him to overcome the AP disadvantage, and time stop lets him deal with just about anything the bear throws at him. Worst comes to worst, Valev uses Kiri to combo the everliving shit out of the bear (Stat reduction allows him to shred the bear).
I give this to Valev, mid-diff. The bear really doesn't have a lot that can put Valev down, much less multiples of him.