well, sonic unleashed was originally gonna be called sonic adventure 3, then sonic world adventure which was gonna be the 3rd sonic adventure game, but then they had to come out with werehog and didnt make it the third sonic adventure. but they might be making a new one late 2009 or antime 2010
Sonic Heroes
Yes there is a sonic adventure 2 battle for the gamecube. I know because I have it~
It is already out. The sequel to that game is called Sonic Adventure 2: Battle. Dx is a re release of sonic adventure, and they also re released sonic adventure 2.
There is no Sonic Adventure 4 Battle, there is Sonic Adventure 2 Battle but that was released 8 years ago.
No as Sonic Advance 2 came out after Sonic Adventure 2 Battle and Sonic Adventure 2 Battle was only made to be compatible with Sonic Advance.
There is no such thing as Sonic Adventure Battle 1, nonetheless no Sonic Adventure is playable on Sonic Mega Collection.
Sonic adventure battle 2
No the Sonic Adventure series ended in 2002 with the release of Sonic Adventure 2: Battle for Gamecube. There have been numerous rumors of a third Sonic Adventure being released but nothing has been released by SEGA to confirm them.
there is sonic adventure 3
Sonic Adventure Battle (DC/GC) and Sonic Adventure Battle 2 (DC/GC)
Rouge can be played as in... Sonic Adventure 2 Sonic Adventure 2 Battle Sonic Battle sonic riders That is all I can think of.
No, Sonic Adventure 2 is only on Dreamcast and Gamecube as Sonic Adventure 2 Battle.