I don't remember Variblume showing up in Gokaiger. o_O

It appeared when they spammed the powers against the Zangyack fleet in episode 50.

Yup, and it was awesome.

It did; they used it to rip off the climax of "MMPR: The Movie" and save a train from crashing.

I just finished the episode. I thought it was pretty cool. I think it would've been neat if Ace and LiOh had a combined form. I do look forward to Go-Buster LiOh. At this point it doesn't look like it will happpen, but I would love if we got a cluster mecha at the end of the show. Everyone hates clusters, but the sheer amount of ridiculous always amuses me.

Edit: Oh, and it would've been sweet if there was a TigerZord also. And then by some miracle, have that, Ace, and LiOh combine. Therefore giving us LaToraTah-OH! xD