I'd watch it

Do we still get the sparkly, spinny transformation sequences, or is it more of a flash, and instead of the worryingly young protagonist, Mo'Gar Skullcrush stands in front of the wizard Balath, who's been causing problems, reaches forward and squashes him flat with one hand.

Either way, I'd watch it.

I think starting out as a standard sparkly magical girl stock transformation, then partway through switching to a more visceral werewolf or Hulk style sequence could be a fun way to do it.
- Basicallt Ben 10 classic series transformations with all the sparks and body horror
- I like it. We could combine it with @sbv@sh.itjust.work 's blood and skulls suggestion for extra pizzaz.
The same style, but instead of cute ribbons of light and stars it's sprays of blood and flying skulls. And the music isn't upbeat, it's screaming death metal.
- I love it, it subverts the trope perfectly. Who do we have to talk to to make it happen?
Sailer moon transformation into anime girls and a parody of the same but dull trash colors with bits of debris and shit flying around hitting them in the face and whatnot.
it's just a deadpan puff of smoke and a "poof" sound effect

This was kind of an episode of Yu-Gi-Oh where the characters all have to play as different cards and go into battles. It was actually pretty good from what I remember.

Season 1 Episode 13. The one where Bakura traps them in a shadow game? That one was always fun. REALLY liked Tristan in that episode as a kid and wasn't sure why.
As someone who has realized they're gay? I now get why.
- For me it was Dark Magician Girl just reinforcing my straightness.
- Isn't that the one where Joey ends up sent into a kind of purgatory and chased by the manifestation of death?
  That was probably originally Hell, wasn't it? They loved sending people straight to Hell in that series. Yami has no chill. You jaywalked? Children's card game, going to Hell.

This is literally just Changeling: the Dreaming.

Plot twist, the anime girl's transformations are the villians.

I like that. The weird mutants from the ~~sewers are the heroes~~ (oh wait, that's TMNT) ~~nuclear cooling lagoon are heroes~~ (oh wait, that's the Toxic Avenger). Fergeddabout subverting expectations, just throw in more anime tiddies.
I could get behind a Jekyll/Hyde scenario with magical girl transformations.