Yeah, the movie was...pretty awful. It was pretty dumb and there wasn't even that much fighting going on. Past Sentai movies pretty much existed to sell a new toy of some sort, and provide exposition for the obligatory "You won't know where this weapon/mecha came from if you didn't see the movie" episode. Since this movie didn't even do that, it literally serves no purpose in the series narrative and can be skipped entirely without missing anything. Which, honestly, is probably the best way to do it.
As far as where it fits in in the series, I don't remember when it was shown but it'd have to be some point after Gai shows up but before Barizorg was killed. Which is probably what, a 7-10 episode stretch I'm guessing?
But yeah. It was bad. Really bad. I was looking forward to seeing more Gokaiger after that incredible ending episode, but...ugh. Left kind of a sour taste in my mouth. Well, I guess it wasn't all bad. Battle Fever theme song was nice to hear.
I spot a putty!
I recognized only a handful of the mooks. I did happen to recognize the Kakuranger ones, which were never in the Saban adaptation, and I also recognized the Megaranger ones since I've seen a few episodes of that series. Didn't see the Ohranger mooks though, but I'm sure they were there somewhere.
Also I didn't recognize anything from that scene with Abrerra. Or even Abrerra himself. I'm guessing he was from Dekaranger though because they used that to fight him.
Those ghost characters were almost toally pointless
They were only there for voice cameos. The ghosts were voiced by Isao Sasaki, Mitsuko Horie, and Tsuyoshi Matsubara.
Mitsuko Horie sung the Goranger theme song along with Isao Sasaki back in the day, and also voiced Sailor Galaxia in Sailor Stars. Tsuyoshi Matsubara sung the Gokaiger theme song. Isao Sasaki has done a TON of stuff, in addition to the Goranger theme mentioned earlier, he also did the themes for JAKQ and Dekaranger, as well as the theme songs of a LOT of other mecha shows such as Casshern, Getter Robo, Space Battleship Yamato, Grendizer, Gaiking, Galaxy Express 999, Gatchaman II, The Ultraman (anime version of Ultraman), Gekiganger III (the OVA release that was the show-within-a-show of Nadesico), and Metalder.
Oh and Kamen Rider.
He also voiced Joe the Condor in Gatchaman as well as a few other voices in a couple of other anime, and he played live-action roles in Kamen Rider ZO and the Dekaranger movie, as well as Juspion (a Metal Heroes series).
So yeah. The ghosts were only there for huge voice cameos, so it's not surprising they didn't play a huge role. And G3 Princess was only there at the insistence of the director, or so I heard.
Ah well. Gokaiger VS Gavan is slated for a March 21st DVD release, so it might get subbed before the end of the month which would be nice.
Other than that, Go-busters is EFFING INCREDIBLE.