I go all 7 Chaos emeralds in Sonic 3 with Tails. I dont know how to transform him. If he can PLEASE tell me I need to know!
From the Sonic 3 page about combining it with the game Sonic and Knuckles:

"It[Sonic and Knuckles] boosted Sonic 3 even farther, Knuckles traveled over new ground in some zones and now there were 14 emeralds. Because of there being 14, you could now access Hyper Sonic, Hyper Knuckles, and Super Tails."

Tails doesn't go Super in Sonic 3--only in the combined Sonic 3 and Knuckles.

--True Red