The characters are from the pilot that was rejected called Pryde of the X-Men. It came out a few years before the X-Men:TAS and Dazzler was part of the crew. This was also the pilot that gave Wolverine an Australian accent and Frank Welker was Toad.
https://www.youtube.com/watch?v=7pNpKytgHaI

But why was Dazzler wearing a headband and a Jubilee-style jacket? None of this fits with the popstar-style renditions of classic Dazzler.

Disco came and went so they gave her something more 80s appropriate? :lolol

The headband is from the first version of Dazzler's blue costume. I assumed the jacket was, too, but I double-checked and it seems that's exclusive to the cartoon and video game. Not sure where that came from, especially since a) Jubilee didn't exist when this cartoon was in production and b) even if she did, everything else was based on the early 80s X-Men line up. Honestly, I'm just happy it wasn't that damn silver disco suit again. I don't know why artists keep insisting on bringing that back.

Watched Avengers 3 Infinity War and Avengers 4 End Game recently.

This could, technically, also fit within the confines of the "Power Rangers General Questions" thread, but it fits more in line with Marvel.

Just how many of the Mighty Morphin'/V.R. Troopers Flip Book issues were released? I have issues 1 & 4.

Was the Masked Rider comic spinoff that was teased in one of the issues even released?

Most hardcore "True Believers" know that each dimension/universe/Earth has its own unique numerical designation, even if said designation is little more than apocrypha on a good day. Even Battle Fever J has a designation! Does the aforementioned "Flip Book-verse" have such a designation?

Wow, did not know these were a thing by Marvel. How does the flipbook work? Do they have a short animation at the corner of the comic book?

It's a double-sided cover. One side is Power Rangers and the other is V.R. Troopers. Regardless of which cover you look at, the alternate side is advertised at the top (so you won't get overly fooled if you're at a shop or convention and find a bagged and carded issue that doesn't show the back, or in this case, the flip side).

I find them interesting and they have unique villains. Seeing a Power Rangers comic centering on Basketball game gambling and Loan Shark creations of Lord Zedd that look like shark men in striped gangster suits with cigars is.... surreal! There's even a letters page in which fans of the time would question the powers that be about inconsistencies between the series and the issues (Professor Hart looks like he's in a lab or control room and delivering orders via communication systems in one issue before it's refined to series standards in subsequent issues).

In the world of classic Rock and Pop, it's a known fact that "Nights in White Satin" by The Moody Blues was released on an album called "Days Of Future Passed".

Has it ever been confirmed if this directly inspired the classic X-Men arc "Days Of Future Past"?

I think it was likely named as a pun on the album title, but I doubt they’d get the whole story out of that (especially since Byrne cited a Doctor Who story as the inspiration)