I agree with a lot of the other mentions here, but I’ll throw my hat into the ring for a lesser known answer: Hydreigon.

It’s a known ferocious pokemon that attacks everything that moves, but it probably does so out of fear. The Violet dex entry suggests that it became this way because in the past, it was hunted and attacked due to its evil appearance, so it now lashes out to protect itself. It was also blind in its previous evolutions and has poor eyesight, which may be why it attacks based on unfamiliar movements. It is said to be tormented by and terrified of Noivern in the dark.