There are a number of puzzles which involve precision timing and grouping of abilities. No Sonic alone stage, no Tails Alone options just forced to group up. You are forced to carrying him along for every stage. Negatively the game falls short with Tails. The one exception is the Special stages from Sonic 2 which aren't dazzlingly confusing with per-rendered CG Graphics but aren't any easier as ring placement and the still slightly sluggish physics make it difficult to collect rings. The levels are actually original this time instead of rehashes from past games the way Episode I did and bosses aren't rehashing either. Sonic won't be getting stuck in loops or on hills this time but Tails certainly won't be a great help in carrying you. To start on the more positive end, the physics have been marginally approved over Episode I's sloppy physics.
With this episode your faithful side-kick Tails returns for some fun but the fun isn't quite enough to save this title.
Sonic 4 Episode II the new and continuation of the Sonic 4 franchise and still can't seem to get the right footing when it comes to attempting to mirror it's Sega Genesis days.