Peps come in three types: power (POW), Speed (SPEED), and defense (DEF).
POW Peps have muscular arms, and they try to attack by punching the bros., which can be countered with a hammer. They upgrade an enemy's power.
SPEED Peps have shark fins, and they attack by trying to dash into the bros., which is countered with a jump. They upgrade an enemy's speed.
DEF Peps hold a shield, and they don't attack in any way. They upgrade an enemy's defense.