Thomas and Twilight Sparkle's Adventures of Teacher's Pet is an upcoming Thomas/MLP:FIM/Disney crossover to be made by Hiatt Grey.
Spot is a dog who wants nothing more than to be a boy, a fantasy he has been fulfilling for one year, dressing as a boy named Scott Leadready II, and going to school with his master Leonard Helperman. Leonard is looking forward to spending the summer with his dog, but Spot proudly declares "I Wanna Be a Boy". Mary Lou Helperman, the fourth grade teacher and Leonard's mother, is nominated for a "Teacher of the Year" award, and given use of Principal Strickler's Wentawaygo to travel to the finals in Sunny Southern Florida, under the condition that no dogs are allowed in the RV. Leonard sadly bids farewell to Spot ("A Boy Needs a Dog") as he and his mother depart.
Spot, along with the Helpermans' other pets, Pretty Boy and Mr. Jolly, are left with a pet-sitter when Spot accidentally sits on the remote and changes the channel to The Barry Anger Show. Anger's special guest is a "wacko" named Dr. Ivan Krank, who claims he can turn animals into human beings, who happens to be located in Sunny Southern Florida. Believing it to be fate, Spot chases down the RV. Spot and Leonard meet up at a gas station. Through many quick costume changes, Spot fools Mrs. Helperman into believing that he is Scott Leadready II and that his family, en route to Sunny Southern Florida, had to return home, but he could still go with the Helpermans. Spot, Leonard, and Mrs. Helperman continue on their way to Florida, singing through all fifty states ("A Whole Bunch of World").
Meanwhile, Pretty Boy and Mr. Jolly, back at home, see another episode of Barry Anger in which Anger reveals that Krank cannot turn animals into people, but rather into terrifying mutant creatures. They decide that they must track down Spot and stop him from being turned into a monster, but Mr. Jolly is afraid to leave the house. Pretty Boy assures him that they can be tough despite their size ("Small But Mighty").
Upon arriving in Florida, Mrs. Helperman goes directly to the Teacher of the Year finals, and Leonard is all ready to play fetch, but Spot has other ideas. He reveals to Leonard the real reason he came to Florida, to become a real boy. Leonard is skeptical, but accompanies Spot to Krank's lab, where Krank has just unsuccessfully tried to turn a frog human. He is ready to destroy his machine when Spot and Leonard show up. Spot tells him that his machine can't work with a frog because it's a lower life form, like his other two creatures, Dennis (an alligator-man) and Adele (a mosquito-girl), and that he needs a mammal, like a dog. Krank agrees to turn Spot human, and gives him a nickel as payment for being his test subject. Krank explains that, throughout his entire life, people have mocked his ideas ("I, Ivan Krank") and turns the machine on Spot.
Spot wakes up to find that he is indeed human—but not a boy as he expected, but rather a fully-grown man (he had forgotten to factor in dog time). Still, he is happy to be human, but the happiness quickly fades when Krank tells him that he will have to travel around with him forever to prove that Krank is not a wacko. Krank locks Leonard and "Scott" up, and hope seems lost until Ian, Krank's nephew and Leonard and Spot's classmate, shows up and sets them free. Krank grounds Ian and sends Dennis and Adele off to find his "dog-man". Leonard and Scott, meanwhile, are hungry, and Scott's clothes from when he was a dog disguised as a boy do not fit his adult body. They see a sign advertising a $100 reward for a lost dog. Scott uses the Twilight Bark to locate the lost dog, along with her four puppies that had been born while she was lost. This prompts the dog's owner to give them $500, as they brought back five dogs. Now rolling in money, Leonard and Scott enjoy a day on the town.
The two lose track of time, but manage to make it back to the Wentawaygo just in time for dinner, forgetting that in place of Scott Leadready II is a stranger who Mrs. Helperman will not recognize. Scott and Leonard quickly make up a story that this new person is Scott Manly-Manning, Scott Leadready II had to go home, and he helped him out. Mrs. Helperman invites Scott in for coffee and soon begins to fall for him. Scott presents an idea to Leonard as to how they can stay together: he will marry Leonard's mother and they'll all be able to live together. Leonard is not okay with this; Scott is his dog, not his dad. Scott tells him he's not his dog anymore. Finally fed up with Scott's stubborness, Leonard disowns Scott as his Dog and he confiscates Scott's collar and tells Scott to leave him and his mother alone. Scott storms off, leaving everyone else lamenting the loss: Mary Lou of her "Manly-Manning Man", Leonard of his dog, Krank of his creation, and Dennis and Adele, along with Pretty Boy and Jolly, search for Spot ("I'm Moving On"). Pretty Boy and Jolly finally make it to Florida, and Leonard tells them the whole story. He comes to the conclusion that the only way he and Scott can be together is for him to go to Krank and have him turn him into a dog. ("A Boy Needs a Dog (Reprise)"). Scott arrives moments after Leonard leaves, and after getting over the shock of seeing Spot as a human, Pretty Boy and Jolly tell him that Leonard has gone to Krank's lab.
Krank plans to turn Leonard into a dog and use him as bait to get Scott back, and then he will have both the boy-dog and the dog-man. Scott arrives at the lab just as Leonard is being strapped to the table. Dennis detains Scott, Pretty Boy and Jolly, but they escape by tickling him. Scott unties Leonard and destroys Krank's machine by inserting the nickel that Krank had given him earlier into a slot on the machine marked "Quarters Only". The machine starts firing at random, turning Krank into a mouse and seemingly killing Scott, turning him into a pile of blue dust. Leonard angrily beats the machine and it fires at the blue dust and turns Scott back into his original dog form. Leonard and Spot reunite, and Spot decides that he is "Proud to Be a Dog".