Lil' Lightning is a slightly obese light orange Pembroke Welsh Corgi with creamy peach fur. He has cream-colored paws and a blue leather collar with a license of a lightning bolt.
He is perhaps a trusted ally at first, but he eventually became jealous of Thunderbolt's fame and attention from ladies, and later schemed to get rid of Thunderbolt so he could take his place on the show. Whilst he can seem sweet and trusty, he actually has an intelligent, scheming mind behind that. Even though he plotted against him, Lightning still does show a bit of remorse and genuine feeling when Thunderbolt fakes his death towards the climax of the film.
Lil' Lightning starts off being a neutral character in the film. Eventually, Lightning becomes jealous of always simply crawling in Thunderbolt's shadow and tricks the German Shepherd into running away by convincing him that the executives planned to replace Thunderbolt with a younger dog. Afterwards, Lightning manipulates the director into re-writing the show slanted towards the Welsh Corgi.
When news of Thunderbolt and Patch planning to rescue 98 Dalmatian puppies from Cruella De Vil reaches Lightning, he realizes that the deed will endanger his chance at fame. He reaches Thunderbolt and Patch in Cruella's hideout and convinced Thunderbolt not to use Patch's stealth plan but to openly attack, which resulted in both Thunderbolt and Patch getting locked up. Lightning reveals himself to be the traitor he is, angrily declaring that he is not Thunderbolt's "little buddy" and reveals to Patch that Thunderbolt is a "fraud" and doesn't care about Patch or his family; he just wanted "his name back in the papers." The corgi then told Thunderbolt that what he said about the German Shepherd being replaced was a lie to get Thunderbolt out of the way and finally be out of his shadow by taking Thunderbolt's place in the show. With his plan carried out, Lightning escapes while laughing evilly, leaving Patch, Thunderbolt, and the Dalmatian puppies locked away.
As soon as the television filming of The Lil' Lightning Show began, Lightning was caught on the driving window of a double-decker bus ridden by Patch during his escape from Cruella and her goons. After the chase, Lightning was overpowered, and taken away by the pound, all while trying to convince the police dogs that he was "helping" Thunderbolt, to no avail. His popularity is lost as well, with a newspaper heading in the credits regarding him as "the unkindest cut of all."
Although Cruella De Vil is the main antagonist throughout the franchise, Lil' Lightning takes the role of the secondary antagonist in this film, with his plan to usurp the fame of Thunderbolt's show, a goal far less sadistic than Cruella's puppy coat obsession.
Lil' Lightning is somewhat similar to non-Disney villain Steele from Balto. They are both canine fame seekers and want to get their rival out of the way so they can keep the fame to themselves (Balto for Steele; Thunderbolt for Lil' Lightning).