>Sonic 1 started the franchise (Sonic 1)
>Sonic 2 improved on it and added Tails and Knuckles (Sonic 3&K)
>Sonic 3 is considered the peak, introduced Shadow and was the last movie to be produced by Paramount before the merger (SA2 and the Death of the Dreamcast)
>Sonic 4 will introduce Amy and Metal and will be the first movie produced after the Skydance merger (Heroes and the first Sonic game developed for 3rd party multi-platforms)
Everything points to Sonic 4 being the Sonic Heroes of the movieverse unless Fowler can save it.