The retiredLightning Costume was at first in an Account Upgrade Set along with the Enpiah Costume in March 2008 and received a proper update in September 2017 after the Fasoro got one in 2016. Putting this on your pet will make them obtain the yellow coloration and spark of Lightning! Lightning pets have their hair standing up from electricity and even zig-zag and bolt patterns on specific ones, much like a Raiju.
The Weather-Like Zoo
Fast as a Blast!
The Lightning Murfin and Snookle both reference the Pokémon Pikachu.