Ali is one of the protagonists in The Land Before Time franchise. She's an Apatosaurus who bears a striking resemblance to Littlefoot, (Ducky even comments when she first sees Ali playing with Littlefoot, "Hey! There are two Littlefoots!") apart from her bright pink skin color and azure eyes. In the TV series, she has a more violet color of skin. She and her mother belong to a herd of longnecks who are related to Littlefoot's grandparents and were forced to leave their homeland due to flooding and excess rain. With their old home turned into a vast swamp, called the Land of Mists, Ali's herd, led by the matriarch called the Old One, was forced to leave.
Journey Through the Mists
Ali and her herd first appears in The Land Before Time IV: Journey Through The Mists. During migration, Ali's herd found the Great Valley and were welcomed by their cousins, Grandpa Longneck's family. Grandpa Longneck fell ill during this time, hereupon Littlefoot and Ali left the Great Valley to search Ali's old home for the fabled Night Flower that would heal him. Cera, Ducky, Petrie, and Spike soon followed them, and met up with Littlefoot and Ali. Together, the group found the Night Flowers and brought them to the Great Valley to heal Grandpa Longneck. They also avoid a belly dragger named Dil and a sharp beak named Ichy who are trying to eat them, until Littlefoot and his friends are saved by a Hydrotherosaurus who chases them away.
Afterwards, Ali and her herd left the Valley to continue their migration even though the narrator said (in the end of the movie) that she and Littlefoot and his friends (Cera, Petrie, Ducky, and Spike) would one day meet again (but it would be another story).
Though fans began to despair of that promise ever being fulfilled, it remarks that the "other story" (made by the narrator in the 4th film of the film series) was seen to be The Land Before Time TV series. Ali returns with the herd in the episode from the TV series, "The Brave Longneck Scheme". She has met a new friend, Rhett, after her herd had merged with his. Rhett tells Ali stories about how he protected his herd from Sharpteeth multiple times. To convince Ali that their stories are false, Littlefoot and his friends made a simulation of how they were attacked by their friend Chomper, a real sharptooth which caused Rhett to run away exposing Ali of his lies, after this Ali knows Chomper and his friendly nature to which he is surprised to see that Littlefoot and gang are friends of a sharptooth.