This is easily the weakest entry of the series for obvious reasons, as it appeared to be your first time doing a sprite movie this ambitious with this many moving parts, with the fight choreography being pretty sluggish and stiff, on top of there being some story issues (for what little a narrative this series actually has), such as Luigi being set up to be an intimidating presence in his first appearance, only for it to fall completely flat as Luigi got bodied the next scene by Devil Mario.
It just felt inconsistent, and I'm not sure why he was introduced in such a fashion if he was going to get stomped right after. I know Luigi is going to lose at the end of the series, but I still think he should have been more evenly matched with Devil Mario at this point in the story, as Devil Mario had not yet collected a Power Star and would still basically be normal-ass Mario.
Even still, this was still a very solid start, with pretty decent pacing, a unique, moody, dreary gothic horror atmosphere that somehow works despite Super Mario being such a happy-go-lucky series and only got better as the series progressed, and the (still great!) custom sprite work inspired by martial arts making it stand out. (Well, I mean, around this time, a bunch of people were doing martial-arts inspired Super Mario parodies, but I think Power Star was by far the most interesting one).
Side note about the sprites, I really miss when sprite animations used Super Mario World edits like this!
Ever since Super Mario Bros. Z came out, Superstar Saga sprites have basically become the meta in terms of sprite animations, and while I think those sprites are really cool, I feel like back before SMBZ became popular, there was much more of a variety of sprite animation styles. Even when the usage of SMW sprites was common, they would still have their own different takes and styles on them.
Like, for example, Power Star was clearly much more martial-arts influenced, whereas something like Rise of the Mushroom Kingdom was more cartoony and stayed more faithful to the games, primarily using sound effects from various Mario games.
Most of the time now, whenever people use Superstar Saga sprites, it basically feels like SMBZ every time.
What I appreciate about Power Star's concept is how much of a breath of fresh air it was compared to many parodies of its time.
Its concept is like, "What if Mario was evil!!11", but not in the form of a humourless "Mario's a violent abuser" gag like most sprite parodies around this time did, but rather making it an interesting, tense struggle for Luigi, as he desperately tries to stop an unstoppable possessed killing machine from destroying the Mushroom Kingdom.
Also, when I was a kid and first watched this flash, for some reason I never realised that Mario was shooting the Boos at the beginning with two Uzis LOL that's so wild