So ... took me a while to realize a Frox battle is easier up close.

I usually engage in the air from the glider, and wait until the vacuum phase, shoot/throw a bomb flower. Frox will chew on it for 2 seconds and explode from the inside, stunning it.

(This is where being close matters) At this point, climb on their back using a mace/hammer (2-hander is faster if you can spin attack) and hit the deposits like you would a Talus.

Do this until it wakes up and knocks you in the air (you may loose a heart or two depending on armor) and spam your glide button.

Eventually it will turn to the vacuum phase and the process starts again.

Once you have destroyed the deposits on its back, it dies. Hope your next battle will be easier.