This is the first boss in Golden Sun: The Lost Age.
Okay, so you move the steaming pot and then after a little walk, you're jumped by 3 apes. Each has 155 HP, so they should be very very easy to dispatch.
Beat Dance - Raises attack for one.
Claw Attack - Attacks one party member with claws. Deadly after Beat Dance is used.
Herb - Takes a turn to heal. Healing 50 HP.
 Battle Strategy
This boss isn't too hard. Just keep attack it with Mars psynergy, and use Felix to heal and you should be okay.
Have Sheba spam Ray and have Jenna spam Flame Wall. Leave Felix to heal whenever possible and when you've KO'd all but one, rush the last one to make sure it doesn't heal itself. They do have Herbs and are one of the few bosses that ever use items within the game. Herb heals 50 HP and that's 1/3 of their life force, so don't let them use it often.