I think the gray background on the KILLER WHALE, Acro, implies that it's in-use on a trophy stand. It wouldn't be grayed out in the book for whatever reason because we only know things get grayed out when they're placed on the trophy stand.
The black border also is just stylish, I figure, because there's a slim chance that out of all the stickers we've seen that happens to be the only "rare" one. Likely the case is either than some stickers just get black backgrounds for whatever reason or there's some mechanic in the game to "blacken" stickers by either powering them up or destroying them (but still cataloging that you had it)--something to that effect.
Andy would make a fantastic character from FAMICOM Wars (Advance Wars in the West), but this doesn't confirm jack.