Currently, we have the Reideen, Yuusha_Raideen, and Brave_Raideen for copyright tags and Raideen for the mecha. I'm not sure which is the Danbooru preferred romanization of ライディーン so that needs to be sorted out. Next, an alias should be created in the non-preferred -> preferred direction. An alias for brave_ライディーン -> yuusha_ライディーン should also be created.* There is also a series simply called ライディーン and already has one post (post #394568). Both series have a robot that share the same name so the mecha should probably have a qualifier.
This series has no relation to the Yuusha Series despite the name.
*I don't actually mean using ライディーン in an alias, it's just a stand in for the correct romanization.
FWIW I've looked at various Tohokushinsha sites like this one and everything is named Reideen officially, so I'm going with that here. Just reverse everything it if's decided it should be Raideen.
Reideen is the very vaguely connected 2006 remake, even moreso than Chouja Reideen, it seems.
Give the robot a mecha qualifier and alias Raideen to Reideen. Or if we're changing Reideen to something else because of the potential ambiguity, give it something like Reideen (2006), I guess.
And a Reideen (series) tag to implicate everything to, which I prefer.
Admittedly Reideen is a little out of my scope, though. Like I have no clue whether the robot should be Raideen or Reideen.
I'm not sure which is more common. I think for the newer series we can use reideen as the spelling because some of the promotional material uses that as the translated name. The older series is a bit more ambiguous.