Focus on getting your Pet Peave from child to adult state as soon as possible. In each state, your monster will have a specific need (for example, playing with rubber balls, eating various things, or listening to music). Meet those needs to boosts the stats of your monster. When you are ready to grow your Pet Peave, shake your device. Even after growing to adulthood, monsters like to play and listen to music. It will not appear as a need above their head, but you can still try an activity. Each time your monsters enjoys an activity, it will receive a stat boost. Once your Pet Peave monster reaches adulthood, send it to battle other monsters.