Largest Ever Pet Shop is an evil, vicious, and malevolent place where pets don't get to hang out with each other, the treats are flavorless and the squeaker toys don't squeak. It's owned by Fisher Biskit. The inside is similar to a prison for all the pets, and Fisher Biskit doesn't seem to care about the pets that live inside of the building. It is the only rival of Littlest Pet Shop. The pet shop has a high-tech security guard robot, which only takes orders from the Biskit twins and Fisher Biskit.
In Terriers and Tiaras it was mention when the producer of Terriers and Tiaras got a call from the Biskit Twins that the Pet Shop has talented pets.
During the finale of season 2, noting the fame that Littlest was getting from entering the International Pet Expo, Fisher Biskit had an entry in the newspapers written to say that he planned to open a second Largest Ever Pet Shop. However, as Mona Autumn would soon reveal at the near end of the finale, it was all just a bluff that Fisher has used more than once before to scare off competition.
As of season 3, Largest Ever Pet Shop has begun to severly lose the war against Littlest Pet Shop- customers don't usually come in, tumbleweeds roll rampantly through the store and the only ones to actually show up on a regular basis are the Biskit family and their employees.
In Hamster Hoods, it is revealed that Fisher Biskit has become so desperate for publicity and profit that he is going out of his way to try and make it seem that Largest Ever Pet Shop is (to directly quote his words) "the ONLY pet shop in Downtown City" (much to the annoyance of local news reporters). Surprisingly, Largest Ever received both due to the thefts occurring at the pet shop; alas, this was a double-edged sword: thefts from the store brought publicity and business, but if they kept up, Largest Ever would go out of business! ...not that there would be anything wrong with that.