Sheldon J. Plankton is NOT pure good and never is. He is a villain most of the time and sometimes an anti-hero. Plus, he has committed several villainous acts and corrupting qualities from what I've remembered.
Also, do NOT add the summary Proposal First on those heroes that have pages on the Villains Wiki as well.
To be honest, I don’t really think it is possible but for Control Freaks to be Pure Good because Pure Goods don’t really act bossy or controlling in nature(though some Pure Goods can be strict at times even when they do it for good reasons).
They are more suitable being under the wrathful and/or heroic disciplinarians categories instead.