Seeking a movie where all the Masked Riders appear

It should be Masked Rider: Heisei Generation, FOREVER. All knights, go civilians.

It should have been a clip when it was released on bilibili, and then someone must have accused it of killing the subtitle team (Baidu if you're interested in knowing the specifics of what happened) and then told UP to delete it, because the Tokio period coincided with the time Tencent was introducing the Masked Riders in a big way.

If you watched this clip a few years ago, it would have been "Heisei Knight vs Showa Knight Masked Knight vs feat. Super Battle Team", with the holster brawl and the ending being trolled for downgrading the intelligence.

All of the above resources are available on Tencent Video.

Added: another possibility is the summer '19 theatrical release, Theater Edition: Masked Rider Tokiō Over Quartzer, also right on your description.