The victory: After a long rivalry and a whole load of third-party interferance by Dr. Robotnik, Sonic and Jet manage to track down a prophesised, supposedly immensely powerful treasure of the ancient Babylonians. But Robotnik has followed them the whole way and forces them to hand over their spoils at gunpoint. They do. Robotnik wins. Sort of.
It's pointless because: The treasure is a carpet. Robotnik is utterly unimpressed and seems to pass out in disappointment (Look, he's really, really unimpressed, okay?) But then, what's this? Tails has noticed that the carpet isn't just a load of old rag, but actually a magic carpet, capable of flight. The thing is, Sonic Riders is set in an age of jet-powered flying hoverboards. A flying carpet is only really impressive if you're an ancient Babylonian. In ancient Babylon. So, er, no-one wins really.