Charo alone was an ordinary kind.
Charo was the only one who looked plain and ordinary.

●Among them, Charo alone was unremarkable.
●Among them, only Charo was a plain sort.
●Charo was the only dog among them who wasn't really special.
●Charo was the only dog that didn't look noble.
●No one here was as plain or ordinary as Charo.
●Unlike any other, Charo was just an ordinary dog.