Sonic 4: What elements would you like to see return?

[Mort]

Metal Sonic as the second to last boss.

The HUGE Sonic 3 & Knuckles style maps with lots of multiple routes.

Most of the zones having unique gimmicks to go along with their theme.

Giant robot final boss (And I mean like the two egg emperors. Not like the Sonic 1 and Sonic 3 final bosses, though cool, don't compare in my opinion).