Could be Gokai Red changing into Hurricane Red and DekaRed.

Actually I think you're right, that makes sense.

I'd be amused to see Captain Marvelous Gokai Change into a duplicate of someone his team is fighting, only to be suddenly walloped - or, at the very least, chewed-out - by his own team.

Can Marvelous do that? Considering everyone has their powers back, so their ranger keys shouldn't exist anymore?

I'm gonna say that Gaisorg is gonna be like Dogold from Kyoryuger. A living suit of armor that takes a host. Either that or he takes their techniques to make himself stronger. From the preview for the next episode, it definitely shows what seems to be a man in the suit (hair style looks similar to Akaningers) and Marvelous notes that Gaisorg used Luka's technique, so it seems highly plausible it is a living suit of armor that takes a host that it deems to be strong and is finding stronger replacements.

Isn't Akaninger on Marvelous's team, though?

Yes and Gaisorg attacks Akaninger and Sasori Orange at the end of the episode. Possibly they have no control or brainwashed. Like I said, similar to Dogold in Kyoryuger when he possessed Utchy.

Gaizorg was Takaharu this episode, so the living suit of armor idea has merit.

what if rita is actually rita from the power rangers universe and not related to bandora at all aside from that

Ep.2 shows that some of the past Sentai members gave Marvelous their Ranger Keys and told him to use them once again.