In Megaranger Ep. 37, there is an insert song during the ground battle when things start going the team's way (trying not to spoil things for those who haven't seen it)! As far as I can tell, it doesn't correspond to anything I'm aware of as far as the Megaranger Song Library! I have checked the PR Wikia, and apparently there is a song popular with Monty Python in the episode, but I'm not certain that is it, but I'm also not knowledgeable in Monty Python either! Please assist if you know what I am getting at, thank you!

Giga booster from Carranger somehow, reminds the jet cannon from Maskman.

So do you guys think there might be a female Red for next year's Super Sentai?

Nope

Could sentai have cosmic deities and entities like Marvel and DC ?

Well, if they want to make a story with that stuff they can. Maybe the mechs are part of a deity's strength? Can work if done correctly

There's any other themes is popular for kids and wasn't used yet ?

Fruit.

Well Gaim's ratings tanked iirc so that might not be entirely true

Gaim sold well with merchandise sales though.