The Legend of Zelda
Aquamentus is fought in the Eagle Labyrinth (both quests) and Demon Labyrinth (first quest only).
If Link rushes into the creatures lair unprepared, it can be a little challenging. Although the fight is easy if Link has a shield. Aquamentus will shoot three fireballs simultaneously at Link, each of which can dish out plenty of damage, but none will even do so much as graze the hreo if he blocks them with a shield. The fireballs can be dodged easily if Link isn't too close. Aside from hte fireballs, the only method this beast has of harming the hero is by bumping into him. Considering how slowly the giant dragon moves, the tackles aren't very threatening. Link can hurt the dragon by attacking its horn with his sword, arrows or well-placed bombs.
Oracle of Seasons
Aquamentus is once again the boss of the first dungeon, known as Gnarled Root Dungeon. Unlike his first appearance, Link doesn't have a chance to "Buff up" before fighting this monster and it gains a new attack which is to tackle Link, but the latter can move faster and he has access to the spin attack, so the fight is actually much easier. Even if the method of defeating him is still the same, Aquamentus seems less able to sustain damage in this game than in the first one.