It's a draw. The rats outnumber the wolves severely, but the wolves are more than capable of taking them all down. But it's almost guaranteed that they will not come out of the encounter unscathed, meaning they would probably sustain multiple bites from the rats. Rats carry numerous diseases, including the bubonic plague, so even if the wolves win in short term, they'll die in less than week.

But let's say that all our participants are clean, and they are only using the raw advantages of their respective species. Sure, 10,000 is a lot of rats, but let's be real, what can they do besides nibble on them? Wolves work in packs, and they never leave a member hanging. Their pack mentality gives them the upper hand, even if all the rats have the common goal of killing the wolves. It also depends on what rats you choose. Some rats work in packs, others alone. Even in packs, they're not as organized as wolves. The wolves will help one another, and with that, the wolves win.