There's also some old unused animations like creating a train, spawning a giant cue stick to trigger Lenny and shooting rockets out of her hat.
She probably has some limit to her capabilities, but she can definitely bend the rules of reality. She is probably just too young and immature for the time being.
Firstly, you can't really use unused animations in a "how strong is a character" discussion. If it's not in any official version of the character's move set, then they can't do it. I wouldn't doubt her being able to, but she hasn't
officially shown herself capable.
Nextly, there is a limit. She makes and does cartoon stuff. She can't bypass that, NOTHING seen in the game (I don't know if Alex has said something somewhere) has given any indication that she can. The link I gave on Cartoon Physics was pretty extensive on that power set. Cartoons can sometimes never die, sometimes they flat out CANNOT be injured in any meaningful way, they can break the laws of physics, but they are still affected by those laws and they aren't able to step outside of their power set.
Here's an example: A person who can literally bend reality, like Scarlet Witch from Marvel, can say "Yeah, there are going to be no more mutants anywhere" and literally alter the DNA of every living Human (including non-mutants) and strip an entire people of their power (even people more powerful than her). Someone with Cartoon Physics can erase and redraw you, bend at unnatural angles, paint things into life (like the train), turn inanimate objects into cartoon characters, have pockets that hold an infinite number of things (though they sometimes comically have nothing in their pockets), etc. But all those things have to be cartoon related, or funny (at least to the user), or what have you.
Why people think Peacock is so powerful is because she is pretty ridiculously powerful.
Paragraph about stuff she can do.
For now, the way she uses it is a very clever mimicry of cartoon physics. Alex confirmed in a lore interview that her powers are still growing, so in all likelihood, she just hasn't fully explored what her abilities can do yet.
So why does she get her ass kicked? Easy. She's an overconfident, cocky as hell greenhorn whose strategy in battle is basically just "throw shit at it until it dies". Against skilled, experienced fighters like Valentine and Big Band, she's naturally going to have a hard time. Marie obviously can just utilize the same projectile spammy tactics as she does. P:
She is probably powerful compared to some of the cast (the only evidence we have are alternate reality versions of events where everyone loses at some point). But she's not at a level where I would even feel confident in saying at her max potential she could have nearly the same level of power as Venus. At her max level I could imagine her being able to create cartoon characters faster, stronger, call more things to her aid, etc. I could also see her creating cartoons without having to think (like she currently does, by blowing a whistle or motioning to give directions).
Also, she technically doesn't teleport, she creates portals at two places and jumps/sticks her face through them. Still an impressive thing, even considering the portals appear to be limited to either holes on the ground or her hat, but not quite the same.
I think one of the biggest drawbacks for Peacock's abilities seems to be her inability to affect the "reality" of anything but the creatures she's created. She barely even affects herself with her powers, but she definitely does not affect other people. She can make portals, so why can't she force an opponent through one? She doesn't appear capable of flattenng someone, a feat other Cartoon Physics characters are capable of. She basically makes Constructs to fight, but that's the extent so far.
Lets look at The Mask. That character is pretty powerful. He is a prime well-known example of Cartoon Physics. That character does not lose. He does not get beaten. The Mask (or whoever's wearing it) can go up against people vastly more experienced with planet-busting power and it doesn't matter cause he's a cartoon, he can just do whatever he wants. Like in the movie, he was able to force other people to follow along with his jokes (the dancing scene). Sometimes his presence alone affects reality (when he won an Emmy). Peacock, since she can get beaten up and lose outright, that's an indication that she's not that powerful. I don't think her body is protected under the Cartoon Physics powers she has, she seems like she could be killed (something Big Band was afraid of and Double was capable of doing in their story modes).
TLDR; Peacock has low-level Cartoon Physics, and not what is commonly considered Reality Warping.