Ok basically during the 1970's a man named Go Nagai created a series of giant Robot Shows, famous things like Marzinger Z, Getta Robo, Grendizer, Gaiking etc.. As far as I know he created the arms firing off from robots. Because these shows were super popular there were many similar shows released. Thus it became a sort of "monster of the week" super robot show show genre.
Gekigengar is basically slagging the whole genre, but its mostly slagging the original Getta Robo. Its not a real show either, some people get confused because there was a Nadesico anime OVA released called "Gekigengar" and basically the guys from the show go to the cinema to watch the gekigengar movie.
As for the Getta Robo's hmm.. ok in the 1974 I think it was, the original Getta Robo was released, it was the 1st ever combining robot show. It never got a western release. The next year in 1975 a sequel series was made with the same characters, but a more powerfull robot was in it and a new enemy, some nazi looking aliens with horns. That was Getta Robo G it was a direct sequel to Getta Robo. This was released in a super edited form in the US as part of a "Force Five" series of animated giant robot shows, this was done in the mid 80's I think. Oh the US version was called "Star Vengers". This does not have a HK version yet, but I'm confident that one will appear because it was re-released late last year on DVD in Japan.
Then in 1991 there was a show released called Getta Robo Go, which I don't know alot about, it is the rarest of the Getta Robo's. Aparantly its some kind of re-telling of the original Getta Robo only with new pilots and now Getta 1 has a cool looking cloak. This also was never released in the west and has no HK version.
If you want to know more about any of this or the genre in general then please ask
