So I finally got around to watching this
It's more or less a 20 minute fight scene. There's almost no story to speak of. It doesn't even have the character dynamic, with Daiji and Sakura only appearing for seconds each. I basically noped out of this the first time I watched it, because I could tell there would be no story implications
That said, I think this is where they introduce the Shark Vistamp. And it's the official first time you see Revi and Vice in action (outside of Super Hero Senki). But sadly, that just amounts to Vice doing his best annoying Momotaros impression while we show off Ikki's hot bod

Watch it if you have free time, but this is totally skippable
The movie ends with Ikki disappearing in the photo like Back to the Future. Still waiting for an explanation for that. It's like one of those series where they decide posing questions is more interesting than creating a story with satisfying answers