To restore health during battle:
If you are in the middle of a battle and low on health, press L2 or R2. Your health will be replenished by your Baku. It will in return take away as many Esamons as you need hearts.

Baku Shield:
Unlock Tumbles Baku Shield by collecting 100 Dream Energies. The first two portals in the temple of dreams must be unlocked.