That Girl Lay Lay follows Lay Lay, the perfect hype girl and best friend that anyone could ever want from their personal affirmation app.
Marky's favorite social media influencer Beastie Pie, is hosting a gross food-eating competition at BoomBox Burger. When Sadie and Lay Lay overhear Beastie plans to rig the contest, they must work together to convince Marky that Beastie is a fraud.
Lay Lay and Sadie volunteer to build houses for those in need, but when Sadie is put in charge of all the workers, managing Lay Lay becomes her biggest challenge.
Trish's college sorority is reuniting for a mother-daughter step contest, and Lay Lay agrees to take over for Sadie, who is locked in a battle with Marky over their personal space.
Bacon becomes the West Packer High football mascot, but when the school's rival steals him as part of a prank, Lay Lay will stop at nothing to get her beloved pig back.
Trying out for the cheerleading squad, Lay Lay and Sadie add their own twists to the routine, but learn that standing out doesn't always work when trying to fit into a team.
Sadie and Lay Lay are assigned a shared Little Buddy, Milaena, they spend the week attempting to create a mini-Sadie and mini-Lay Lay, or "Say Lay", instead of learning about what Milaena likes and what makes her unique.
The Alexander family looks to Lay Lay to cast the deciding vote on family decisions, but the newfound power goes to her head, and one ruling causes a rift between her and Sadie.
Sadie and Lay Lay are enlisted to help save the school's boxing club, and set up a fight between Sadie and Gigi that is sure to draw a crowd. Now all that's left to do is train Sadie to fight. How hard can it be?
Hoping to change her reputation at school, Stella tries to prove that she's not the teachers' pet.