joke entry obviously, but i mean… it uses sonic 3 gameplay sprites, it introduces a new playable character and brings back all the existing ones… technically!
Sonic Generations
(the 2D half of the game)
Sonic the Hedgehog 4
No.
Sonic Advance
Sonic the Hedgehog Pocket Adventure
Sonic Adventure
Sonic Jam
Sonic Robo Blast
Sonic R
Sonic 3D Blast
Sonic Blast
Sonic the Fighters
Knuckles' Chaotix
Sonic the Hedgehog: Triple Trouble
Not as much as the fan remake, but Knuckles does reappear…
Sonic & Knuckles
Intended to be the second half of Sonic 3, but you could make the case that this released as the fourth mainline game due to its standalone capability.