Chestbeater enemy line

Chestbeater and Wild Gorilla are species of monsters found in Golden Sun: The Lost Age. These monsters, resembling large, bulky apes, are palette swaps of each other and have differing levels of power and defense. One of these monsters, the Chestbeater, serves as a full-fledged boss monster. Both members are featured in the earlier stages of The Lost Age.

Chestbeater
The Chestbeaters are members with brown fur and blue skin. It has 155 HP, 44 Attack, 11 Defense, 20 Agility and 24 Luck. Its resistances are highly lopsided; it is resistant to Jupiter attacks and highly susceptible to Mars attacks. It is evenly resistant to Venus and Mercury attacks, although the party likely doesn't have access to the latter at this stage.

A Chestbeater can attack physically and use the monster skills Beat Dance, to increase their attack power, and Claw Attack, for enhanced damage to one target. They also carry two herbs to restore roughly 50 HP.

Only three exist in the game, as the boss of Kandorean Temple as the final challenge before earning the Lash Pebble. Since they are also the first boss in the game, they aren't very tough to defeat. A good strategy is to give Sheba the Mysterious Card so she can use Juggle, while Jenna uses Mars psynergies and Felix keeps everyone healed up.

When playing on Hard Mode, however, these bosses become a bit trickier. Considering the limited access that the party has to healing items and Psyenergy at this point of the game, it is difficult in Hard Mode to keep everyone's HP high and still leave Felix with enough PP to continually heal the party in the battle.

Felling a Chestbeater yields 40 EXP, 28 Coins and a Nut. Combine all three together, the total reward comes to 120 EXP and 84 coins.

Wild Gorilla
A Wild Gorilla is a large member with purple fur and beige skin. It has 130 HP, 122 Attack, 32 Defense, 76 Agility and 5 Luck. Its resistances are highly lopsided; it is resistant to Jupiter attacks and highly susceptible to Mars attacks.

A Wild Gorilla can attack physically and use the monster skills Beat Dance, to increase their attack power, and Ransack, which is similar to Chestbeater's claw attack, albeit more powerful.

Felling a Wild Gorilla yields 77 EXP, 80 Coins and in seldom cases a Bramble Seed. They can be fought on Gondowan Cliffs and Kibombo Mountains.

Crazy Gorilla
Like with all other monster lines introduced in The Lost Age that have apparently only two members, a third palette swap member to this line exists in the code of the game cart and was even given its own name, but has none of its stats and abilities coded beyond weak placeholder abilities. Had it been used it would have appeared as a green-furred, purple skinned member named Crazy Gorilla.