Monster

Monsters are creatures that are fought throughout the Golden Sun series. They appear all across Weyard and make up a majority of the opponents fought in the series, including several bosses. They appear in large varieties and vary in strengths, weaknesses, and abilities. Monsters that are identical in appearance but different in abilities, color schemes, and occasionally size are said to be part of the same "Monster Line".

In gameplay, Monsters can be fought to gain experience and coins. Most wild monsters (those that are fought in random battles) also drop items which can vary from cheap, common items, to rare artifacts.

In terms of capabilities, nearly all Monsters are capable of attacking physically. Most also possess Monster Skills which, unlike Psynergy, don't consume PP and can therefore be used unlimited amount of times in battle. Some monsters, usually but not always stronger ones, also possess limited Psynergy abilities in addition to or instead of Monster Skills.

In Kibombo, a girl commenting on some meat roasting nearby, makes the distinction between Monsters and regular animals, indicating that there is an in-universe difference between the two. Various other NPCs hint that this distinction is due to animals coming into contact with Psynergy Stones, spread across Weyard following the eruption of Mt. Aleph.

Trivia
Monsters apparently existed in Weyard even before the eruption of Mt. Aleph, as several of them are battled in the game's prolouge and within Sol Sanctum. A simple explanation for this is that they lived in close proximity to the alchemical mountain and the large Psynergy stone at the Vale plaza. This raises the question of where the Valeans attain their meat.