I personally think some animals are evil but only one species in the sense that they're truly evil. Mostly its that I dislike their completely normal natural because of what they do (like water buffalo stomping on lion cubs) and therefore dislike the species, not that I actually consider them to be evil beings.
I believe animals have personalities, to some extent, and individual differences but wild and pet animals aren't quite the same with it. This topic seems to be mostly about pet animals and dogs so I'll focus on that. I don't think dogs can be "evil". Mean, nasty, angry, etc... of course they can be. But not evil.
A lot of dogs can be saved with training, even if they're old or "far gone". This doesn't apply to every dog of course but "how they're raised" isn't the only factor! Dogs that have been neglected and abused to the point of becoming aggressive or mean can sometimes learn to move away from those behaviors. They might still have issues, like not being able to be around cats or children, but I strongly believe in giving dogs (and other pets) a chance to re-learn things and get a second chance at life.