Well, she could always smash the plastic partition between her and the pizza; it's hard to go wrong with a good smash. Then there's all those pizzas to dump on the floor! And if she looks farther back there are bags of cheese and tomato sauce she can throw everywhere, and an oven that will burn most things she could put in it! There are not nearly enough things burning right now; she should fix that.

Those all sound like GREAT IDEAS!

The plastic partition was designed to stop sneezes, not rampaging teenagers; it's not hard to rip it off its mounting points. Turning the floor on both sides of the counter into a pizza swamp is also trivial. If she wants to get to the oven, she'll have to vault the counter, and the people cooking the pizza have had time to realize what's up. One of them has just put a pizza in to cook and is still holding the big flat shovel, now in a much more militant posture.

That oven can set things on FIRE! She's going for it. And hey, that pizza shovel looks like fun, she should take it away from him and thwack something with it!

Now she's wrestling a probably-evil cook for control of his pizza stick! Also Katie has apparently learned how to look on the bright side, i.e. she has stopped crying and started throwing random objects at the lamps over the counter, so the wrestling match is happening on a battleground of tomato sauce and glass shards.

Probably this is objectively concerning or something but right now somebody has filled April with the desire to destroy things and she is turning it back on them and this is TREMENDOUS FUN. Whee!

She loses her balance to the tomato sauce and a small amount of blood to the glass shards but in return she gains a pizza stick, and there are so many things to bash with it!

A ringing voice calls out, <Say 'Lunar Guardian combat form!' It will help you defeat them!> The phrase sounds oddly familiar, as though it's the sort of thing people say all the time. Also, the voice isn't coming through April's ears. It's just showing up in her head, clear and confident.

"—what, how, why, how—?!"

<It will transform you into the form that will let you use your powers. I know that doesn't make sense, but I'll explain everything once you've taken out these villains.>

She attempts to formulate the reply <fine I'll roll with it but if you're messing with me you get a pizza shovel to the face> and then, with teenage self-consciousness battling the strange feeling of familiarity to an overall result of conflicted embarrassment, says "Lunar Guardian combat form!"

Time slows down, or perhaps her mind speeds up, because she and everyone else in her line of sight are suddenly frozen mid-pizza brawl.

Points of silvery-white light spring up around her, multiplying into a cloud of glitter and then condensing onto her skin. Her hair pulls itself out of her face and something materializes on her forehead. Her clothes melt instantaneously into a white jumpsuit with high boots and shoulder-length gloves, gold accents and a blue skirt.

Stranger still are the new structures unfolding in her mind. She can see the effects of the pizza in herself, and on the man who's grabbing her arm, and she knows it is the work of an enemy, and that with a whisper or a shout of "Moonlight Clarity!" she can sweep it away like mist.

And once she's had a moment to process all of this, time goes back to normal.

Fine, "Moonlight Clarity" then. If she finds out who set the requirements for this magic system she is going to be sorely tempted to hit them with a pizza shovel.

Chaos and disorder suddenly stop feeling fun. Wow, this is a huge mess. The rightful owner of the pizza shovel seems to feel the same way; he stops trying to reclaim it and blinks like someone woken up mid-dream at three in the morning.

Okay, she has officially abandoned all pretense of not being in open opposition to the pizza demons, so might as well own it. She hops up onto the counter with her pizza shovel and looks around for anyone who seems like they might be inclined to protest her interference - and, she supposes, for other pizza victims she might be able to help.

There's two more pizza stand employees coming at her. Katie has killed all the lights and moved on to dual-wielding the mustard squirt-bottle from the Burger King and the hot sauce squirt-bottle from the Panda Express all over the tables and her by now extremely angry friend. Also the mall cop has apparently dealt with College Boy and is on his way in.

<Excellent work!> Says the voice in her head. <You can release the others if you touch them!>

Keeping the pizza shovel ready to hand in case of opposition, she starts booping people and muttering her incantation as rapidly as possible. Pizza stand employees first, then Katie, at least if the pizza stand employees are both actually mind-controlled and not secretly pizza conspirators who will need to be shoveled until they sit down...

All the pizza humans see the error of their ways as soon as they get Moonlight Clarity'd. They start mopping up the mess on the floor (somehow April's jumpsuit is completely spotless), and Katie starts apologizing profusely to her friend. The mall cop asks "What do you people all think you're doing?!"

<And now would be the time to get out of here. Don't worry, nobody will recognize you untransformed.>

"Well for starters I'm apparently a superhero," says April, ignoring the mysterious voice because she wants to find that college boy and boop him. She does leave the shovel with the pizza people, because it would seem unfair to just walk off with it.

The mall cop has enough people to question and/or check for injuries that he's not going to try to stop the person who's least covered in condiments from leaving. 

A black cat trots up to her on the way out. <You're a Celestial Guardian! Not too different from being a superhero, I suppose, though the scope is larger. If you're looking for the other victim, he's this way.> The cat darts to a place where another corridor branches off from this one.

"You're a cat," April observes, but she follows the cat regardless, because at this point why the fuck not.

<It's convenient for some things. And technically we're both reincarnated space aliens. Anyway, he's in here.> She points a paw at a door labeled "Security"; angry voices are coming from the other side.

Angry voices! Her favourite! Actually the opposite of that, but fuck it! Into the Security office she goes.