Eh, here's six more things it'd be neat to see in SRW Y. Some returning, some new, one very unusual but could definitely work if handled well.
Tekkaman Blade (TV Series): An anime tokusatsu style show mixing power armored characters with transforming super heroes and villains, Tekkaman Blade has been in some handheld entries of SRW before, but it would be great to see it in a modern game. It would be especially cool to see alongside the newer ULTRAMAN series or, if it ever happened somehow, a Super Sentai series inclusion. It's a fairly dark series with an often sad tone to it, but Tekkaman Blade is a very good show that is well worth checking out. Just make sure to stick to the original Japanese version and not the Saban dub/re-edit version titled Teknoman.
Macross Zero (OVA): I have generally mixed feelings about the overall quality of Macross Zero as a series, but there are some solid elements that could definitely work as part of a larger SRW story. Additionally, this would allow the use of Variable Fighters that are closer to the ones in the original Macross without necessarily stepping on Harmony Gold's toes, along with featuring Roy Fokker as a character. My biggest reason for this comes from a frankly impossible idea where the tech from this series could be combined with a bit of narrative and character from the next series on the list.
Area 88 (Manga, OVA): This would be the wildest series I've mentioned in all of these to actually include. A 1980's manga centered around a young man who gets tricked into signing up for a three year tour of duty as a mercenary, Area 88 is a likely inspiration for Cross Ange, among a very good number of other stories centered on the cruelty of war and its destructive results on all those involved in it. It would be facinating to see the characters of Area 88 end up using unique Variable Fighters to combat earthly and otherworldly threats while contracted by the heroes in SRW, but oddly I think the lack of a really clear and obvious big bad for the introspective story would be the biggest hurdle of all to a satisfying inclusion in an SRW title.
GEAR Fighter Dendoh (TV Series): Technically something of a "we have a Brave series at home" option, Dendoh was directed and written by the same husband and wife team behind Gundam Seed. Dendoh is a standalone anime directed more at younger audiences, and centers on Ginga and Hokuto, two boys who are nearly nothing alike in personality and interests, being forced by circumstance to work in sync to pilot the GEAR Fighter Dendoh to combat an alien invasion. If you like the synchronized dual pilot concept from Pacific Rim, then you might be interested to know that Dendoh did it first (just without the drift concept). It would be a nice option to include, especially if there aren't any Brave series already included.
Aquarion EVOL (TV Series): Hey look, it's the best Aquarion series (unless Myth of Emotions is better, IDK). Honestly at this point, there's probably a bit more of a chance of either Genesis or Logos getting in over EVOL, but I would much prefer this one. I had a lot of issues with Genesis, most of which can be ascribed to my issues with Shoji Kawamori as a writer. His biggest problem is sudden and unexpected swerves in the plot that come out of seemingly nowhere and often undercut elements or moments that came before. He's also really not a subtle man, as his writing in Arjuna will clearly demonstrate. Subtlety isn't always good, though, and his surprising turns in the plot can sometimes be truly amazing. EVOL actually uses a scrapped plot twist from Genesis to recontextualize so much of that story that it manages to actually fix multiple problems I had with Genesis in one fell swoop. I also very much prefer the characters and mechanical designs from EVOL over Genesis and Logos, making it my go to series for an Aquarion inclusion.
Gundam Build Divers Re:Rise (TV Series): Hey, did you know Gundam did a virtual world isekai series? Did you know it was really, really good? It was so good, in fact, that it elevated the woefully disappointing Build Divers simply by building on that series most interesting narrative element. Re:Rise has all the character development, emotional turmoil, and concrete stakes that were completely absent from a lot of Build Divers (until the last arc). Additonally, it has the incredible Core Gundam and its modular weapons and armor systems, really taking advantage of the potential of plastic model kit bashing. If the Build subseries gets an entry in SRW Y, I really hope it's this one.
And that's it, hopefully for real this time. I had a few ideas on this list before starting but struggled to find a closing option, so here we with 30-ish different series that would all be interesting inclusions to the newest game in this long running franchise.