If you feed Tales-Of-Pirates-II pet with energy food successfully when it's growth bar is at it's maximum, you will gain a level. There is a certain rate of failure when you feed your pet fairy with any energy food. Success rate becomes lower as your pet becomes higher in level. If successful, the whole growth bar will be depleted. However, if you fail, half of the growth bar will be depleted.
Your pet will be able to learn skills(Tales of Pirates 2 Gold) from different scrolls and skill books available in the game. A pet fairy can have 3 skills in total. When a pet fairy uses a new scroll or skill book, there will be a chance that the new skill will overwrite one of the existing skills it possesses.
There are 3 different grades of skill to be learnt: Novice, Standard and Expert. A skill of higher grade will overwrite the same skill of a lower grade.
Protection When the characters HP falls below 20, it will absorb all normal damage done to the character.
Berserk Character will have a chance to do double damage in normal attack.
Magic Increases magical damage of the Herbalist and Explorer class.
Recover Increases HP recovery rate of character.
Meditation Increases SP recovery rate of character.
In a word, the highest level for the fairy should be Lvl 50.