What is Fire strong against in Aniimo?

The damage boost depends on the element of the skill used, not your Aniimo's type.

Exploiting a Grass or Ice target requires selecting a Fire-element ability during combat. An Aniimo of any typing deals the 1.6x multiplier as long as the specific attack is Fire, whereas a Fire-type Aniimo casting an off-element move gains no bonus. Combat does not incorporate elemental chain reactions, meaning the interaction applies purely as a direct numeric damage increase.

Grass targets are occasionally referenced as Plant in game descriptions, but the interaction functions the same way. While offensive advantages rely entirely on the ability selected, defensive vulnerability depends strictly on your creature's assigned type. A Fire-element Aniimo remains weak to Water attacks and Dark attacks regardless of what skills it equips, meaning offensive advantages should be balanced against the risk of incoming elemental counters.