I love practicing Gamma's story, but I can't seem to find a fast way to unlock his story so that I can practice his Hub World skips. Just watched the WR of his story and I saw that they only had Sonic and Gamma unlocked??? How is this possible, is that possible to replicate on PS3 or GC?

This never got properly answered, sorry! The fastest way to unlock Gamma would be going through Knux's story, as Gamma is unlocked before Knuckles boards the Egg Carrier. If you're running on console and constantly having to reset, your best bet is removing your memory card or playing without saving to prevent having to re-unlock characters for attempts.

As for the run in question, please let us know which run you're referring to with only Sonic and Gamma unlocked and we'd be happy to investigate further. I've checked the current WR ( 9m 33s 070ms - Niczur ) and he has every character unlocked at the start.