Thank you for checking out Kroom!
You can dodge Biboo's attack by hiding behind the air wents. And you can just shoot her down fast if you dodge the pebbles.
The game is on the more difficult side, for sure, this is why we included the "Tips if stuck" option in the menu :) After the jam, we plan to work on tweaking the fights, the later ones aren't as intuitive as we thought.
Again, thank you!