I did beat Linnea after getting the glide shroom and health items, she's fair enough once you have those (except for that one attack from that one spot), and I beat Momo with Linnea's sword and using health items.
...Wait, the I-frames for the dodge last that long? There's no indication they should last that long.
...So that's the run key, I guess I confused "Dash" with "Dodge" when I glanced at the keybinds before. 'XD