Ok, this battle is just bad from the very start. You should never give the enemy party the chance to stun you. In the same vein, don’t use moves that waste turns, unless the enemy either can’t move in that turn, or it will be incredibly useful. Transforming was a waste of a turn.
 
The decision to use “tail slap” was a bit stupid, what’s it going to do, even if it does hit? You’re in midair, he’s still going to hit you. Personally, I would’ve used “Hydro Cannon”, the name suggests it has force behind it, and given the references in this comic it’s likely similar to Pokemon in that it’s a “breath” attack, which means it doesn’t matter if you’re in midair. It’d force Regis down, and somewhat force you up further. Then, given his skill, you wouldn’t go for an attack, he’d move out of the way. You’d try to safely land, or use something that allows you to safely land while getting him out of the way, if he doesn’t move.

@lance blazer  
Not, but she have other options too.  
Like diamond dog form, or pony form.

This doesn’t look good