Most of tribute episodes in Gokaiger has previous Super Sentai openings in instrumental version during Gokai Change fights. Example: Gaoranger opening instrumental version is played during Gokaiger episode 9 (Gaoranger Tribute). But why in Gokaiger episode 7 (Gekiranger Tribute), Gokaiger Episode 28 (Jetman Tribute), and Gokaiger Episode 44 (Battle Fever J Tribute) not have previous Super Sentai opening theme songs in instrumental version?

Artistic choice perhaps?
Just remembered that they did not have their respective instrumentals for those eps.

There is one other exception, which was Ohranger and that is that "Ole Ohranger" was ditched for "Niji-iro Crystal Sky" when they had the Ohranger guest episode. Thing about that though is that Niji-iro Crystal Sky was originally intended as the opening theme prior to Ohranger's airing but it got replaced by Ole! Ohranger and was used as an insert song instead. And from what I have heard hardcore Ohranger fans prefer Niji-iro Crystal Sky as the true theme song to Ohranger apparently.

After I am watching Gokaiger Episode 31 (Ohranger Tribute), I am trying to search Ohranger songs (Niji-iro Crystal Sky) in Youtube. Yeah this song is really good.

I am love Ole Ohranger and Niji-iro Crystal Sky song.

Ohranger possesses the greatest soundtracks in the Sentai history.

I looked it up. Can't speak for Jetman's tribute episode, but the Battle Fever and Gekiranger episodes have theories or explanations to the matter.

Gekiranger Tribute: http://powerrangers.wikia.com/wiki/E...p%C5%8D_Lesson

Battle Fever J Tribute: http://powerrangers.wikia.com/wiki/E..._Christmas_Eve

Questions about sports themes in suit designs

A): Was Dynaman originally intended to be baseball-themed? I've heard this and it's believed that the suits look they way they do because the sports theme was dropped, but the suit motif remained.

B): Was Zyuranger partially inspired by sports or athletic designs? Saw archival footage where supposed athletes wore a (navy) colored outfit with a white diamond on the chest and white "belt", which echoes the Zyuranger design. It was old Soviet sports parade footage, but I cannot say if the outfit design is based on the sport itself or Soviet-state coloration. To be honest, I don't even know what sport this would correlate to.

How would be mechas based on Aquarius and Libra signs ?

Literally Tenbin Voyager. How could you miss that?

I don't watch sentais.

1. Then why do you care to ask?

2. I'm not watching Kyuranger and I know that TenbinGold/Voyager is Libra-themed.