Ochaco doesn't need a nerf to her HP
Ochaco's HP isn't the problem it's her damage from her combo, and how hard it is to dodge the circle of her gamma.
I can see why she has 300 HP when she is so vulnerable when attacking because she is immobilized and can easily be targeted when she uses her gamma mid air, and is floating when she swings her car, so she is a fairly easy to snipe down during that time.
It's so hard for her to leave a fight if you corner her and because it takes a second for her to grapple onto something it's better for her to have that extra 50 HP. Her mobility isn't as instant as characters like Iida, Mirio, Rapid Bakugo, or Hawks. And she needs a milesecond to start moving compared to other rapids
She's similar to Twice (Who also has 300 HP) where it takes a bit of time to use his gamma and get away because there is a start up to it, so his movement is a bit lethargic in a way.
My point is nerfing her HP won't change anything. And she has a very high skill level compared to some demons with some bullshit tracking -cough- T W I C E
Yes I agree she should get some nerfs specifically to the damage she can do with her combos. But not to the HP.