Includes opponents that move/act in significantly erratic fashion, making defeating them a challenge mostly due to this. Often seen with them flailing their primary weak point in a way that's hard to follow accurately.
Alternate names: Staggering foes, Wobbling foes
The first video game about Erratic foes was released on October 13, 2008.
Staggering/wobbling synonyms are there for instances when they do it all the time.
Not including enemies that only have animations for this but don't really affect how easily they're defeated (such as no weak points to aim at).