No the Sonic Next Generation game does not have Xbox Live. But it has downloadble content in it, for you to get new stages and etc. Now as if for Sonic Unleashed it doesn't have any Xbox Live too, it just has downloadble content and that's it. And for Sonic's Ultimate Genesis Collection (EU name Sega Mega Drive Ultimate Collection) it has the same thing as the others. As if for Sonic and Sega All Star Racing is the same thing as the other three sonic games. thanks for asking!
off of xbox live man
Yes there is. You can get it from XBOX live arcade for Xbox 360.
Theres a sonic game for XBOX 360, but I forgot about it for the XBOX
While nothing can be definite without consulting a SEGA official, most likely Sonic Adventure 2's final port will remain on the Gamecube as Sonic Adventure 2 Battle. Well, since they made Sonic Adventure for Xbox LIVE Arcade, and the DX version, most likely it will be on Xbox LIVE Arcade
Xbox LIVE Marketplace, or PSN Store
PlayStation Network, Xbox Live Arcade,
Sonic the Hedgehog 4 itself is playable offline but you need an internet connection to buy the game first.
soiljaboy47 is his xbox live name
Sonic the Hedgehog 4 is only available by download, off of WiiWare. PSN, Xbox Live and iTunes.
No but you can download special game modes for a small fee.
Xbox Live