From what I understand, Sonic is actually unable to time travel, stop time, or teleport on his own, as he needs the Chaos Emeralds to do so, and in the case of traveling through time, he needs a partner with another Chaos Emerald to do so, or those Time Signs in CD.

The Star Spirits, Crystal Stars, and Pure Hearts can do a variety of different things BTW.

If they truly had infinite power, then how come they were completely drained in Unleashed?

FYI: The Star Beam, Crystal Stars, and Pure Hearts are capable of nullifying any and all invincibility, rendering any of Sonic's super forms useless in the long run. Also, Hyper Sonic isn't even canon anymore.

THIS