Beyond Generations is even more evidence of it being Reiwa Megamax because the future rider is also gone berserk just like Poseidon

Drive turned evil in the Summer Movie. Was his summer movie Megamax?

Bad analogy. Drive's' Summer Movie was, infact, a summer movie. Whereas Megamax was the yearly crossover flick.

It's just a joke, man. You ain't gotta take it literally. But my point still stands, joke or not.

-Crossover movie featuring the 2nd and 3rd rider of their respective era (OOO/Fourze, Saber/Revice) and the showa riders
-Movie features a movie rider/s from the future that has gone berserk

And here's the big trailer:
http://https://www.youtube.com/watch?v=G_z5kqd8tu0

Everybody's here!

Also, Century has a scarf!!! I already love it.

Damn, I was not expecting to get other Kamen Riders, even though they're just summons.
That guy at the end must be old George.

I wonder what those bigger stamps Olteca had in the case are for.....

Another conflict between father and son....(again)

Sakura became a Rider just in time to join the group shot.

Do the Deadman end up teaming-up with Shocker?

So Old Man George can summon Riders (living the fanboy dream) and it seems like Shocker has a legion of evil Riders including Ohja, Eternal, and Sorcerer.

I wonder when Ichigo shows up.