Sonic and... stuff...

[Pigyman]

4) Better VAs. "FROGGIEE WHERE ARE YOUUU???!!!" (All 3-D Sonics.)

I don't remember that in SA2. Plus, Froggy is da bom.

Me neither, but Big was in SA2. After fighting Rouge/Knuckles in Mad Space/Meteor Herd (Dreamcast version only), during the cutscene if you repeatedly press A,B,A,B, Big will run through the background.
http://www.youtube.com/watch?v=en_wGV0FFQE

In the GCN version you could do that during the scene where Amy talks to Shadow before fighting the Biolizard. But he still did not ask where Froggy is.