The best I've seen was a rainbow quiggle, not good stats, but it was colored, but this was when rainbow paint brushes weren't really valuable.
A couple of weeks ago a lot of people were dumping painted pets into the pound. So I got to see a Darigan Kougra & a Faerie Lupe.
Best I've ever seen in the pound was one of the "specific" avatar pets - ie, Orange Grundo, Island Quiggle.....can't remember which one exactly. Nothing too special though xD
It's been along time since I was last pound seraching but my Favourite pet came from the pound Mastea. This was like 7 years ago but was a super good nab
I've seen a few UC's before in the pound, and tried to get a BN pirate at one point, to trade on of course but my computer isn't fast enough.
yellow kacheek with decent stats. 70ish hp, 55 str boost. i dont really visit the pound often, i haven't really seen any painted pets.
There so many since im one of those "evil pound lurkers" Hava to say (what i consider my best yet) a Mara. cybunny then traded for a Poogle. Hmm
wasn't majal_kita in pound at one stage? i remember it being their a few years ago for like almost 1 billion neopoints