Kuuga, Agito, hibiki, kabuto, kiva, w, fourze, wizard, and drive need to make an appearance. Deno is just a movie exclusive cameo. Ryuki, faiz, blade, deno, decade, os, gaim, ghost, exaid, and build made an appearance in zio. Zio possess 10 Neo heisei, kuuga, faiz, and decade. Blade and ryuki are unknown so far. Agito, hibiki, kabuto, and kiva are ones that need some sort of relevance or tribute via another, watches, or straight up cameos.
Kuuga- receive the watch after using the form, fought another kuuga,No Joe
Agito-N/A watch, N/A appearance, no another
Ryuki-N/A watch, but ryuki time will fix that despite already did a ryuga two parters.
Faiz- Accomplished all 3
Blade-we'll see if the watch is created or not. Did 2.
Hibiki-N/A for 3
Kabuto-N/a for 3
Deno-No watch despite fighting another deno with Ryotaro in the movie?
Kiva-N/A for 3
Decade-the special watch he created himself?
W-did 2/3. I don't see a w special, but there's ghost and ryuga, so there's hope.
Os-done all 3.
Fourze-Extra staff replace fourze.
Wizards-Beast replace Haruto offscreen.
Gaim-done all 3.
Drive-geiz possess it. No tomari. No another drive.
Ghost-done all 3 despite geiz already possess it.
ExAid-done all 3
Build-Done all 3
Zio-surprisingly done all 3.

Yes yes yes to Chalice, Amane, and Kenzaki coming back!

Looking forward to this!
And Diend too? All the yes!

If rumors are anything to go by, apparently some twitter user saw them filming an episode with Agito, apparently relating to Trinity.

I had my doubts about if we were going to see the phase 1 Riders get any spotlight outside of Ryuki and Faiz but at this point they have a cheap way to not need suits for Phase 1 forms thanks to the Decade Ridewatch.

I think as far as the writers are concerned Heisei Gens Forever was Den-O's, Kuuga's and Double's tribute ( Double was meant to be the big surprise come back but when they found out Suda was booked up they changed focus onto getting Den-O's actor back). But for all we know the Summer movies bring back the last remaining actors, I'm just gonna enjoy the ride and scream loudly at 1:30 am every time they anounce a new returning actor in the episode preview.

You know, Agito being involved with Trinity makes perfect sense considering Agito had Trinity first

I really want Overlord of Darkness are appeared in Agito Tribute Episode....

Shouichi's actor made a voice cameo in HGF, similar to Ryuki's, so I'm thinking he'll make a proper appearance in the show.

Better than his role in decade one sec cameo summer movie. Anyway, summer movie nowadays tries hard to fit in the continuity, but end up being worse, so I rather its an alternate ending or something else entirely. I'm curious if there's a movie exclusive form with ohma and jackers.

on the one hand I'm happy to get tribute episodes and some actors coming back until the end.
on the other hand it means the time jacker creating Another riders plot will be here until the end game and the overall story wouldn't develop much during the entire series.

Remember when we got one MOTW that wasn't an Another Rider? That was kind of weird.

I wouldn't be too surprised if we got a few more Another Riders, and Another Decade as a final-ish boss as some people have suggested could work. They're sort of going for inter-Rider conflict but with only 3 (sometimes 4) Riders, so I guess there's a limit to how far that'll go without repeating (which we kind of have already)

Just like gokaiger after 3/11 a lot of vet came back and villains get shafted, but like lupin and boukenger it's a character driven series full of fillers especially with gai.