In Alice in Wonderland, Alice does her share of shrinking and growing throughout the movie, yet her entire outfit (dress, stockings, shoes, etc.) fits her perfectly the whole time.
Averted in The Ant Bully where the wizard ant's magic for some reason cannot shrink clothing.
This is both averted and played on in Brave. When Queen Elinor changes into a bear, her clothes are torn and left behind, similar to Tiana. However, whereas Tiana gets a fancy foliage-inspired wedding dress when she turns human again, Elinor remains naked, only covered by the tapestry she and Merida assumed was necessary to facilitate the transformation.
When Yzma accidentally turns Kuzco into a llama near the beginning of The Emperor's New Groove, Kuzco is still wearing clothing when his face becomes that of a llama's, but Kronk stuffs him inside a burlap bag as he is still transforming. When Kuzco is finally freed from said bag by Pacha, he has already finished transforming into a llama, and his clothes are nowhere to be seen! (they are replaced by red fur colored to resemble his clothing) At the end of the film, when Kuzco defeats Yzma and turns back into a human, he mysteriously gains his clothes back.
Lampshaded in Hotel Transylvania, where Jonathan immediately wonders if Mavis, Dracula's daughter, was wearing tiny bat clothes when she transformed from bat to human. While she obviously isn't wearing clothes as a bat, she does at one point transform while wearing a Hawaiian shirt, which shrinks to fit her bat form.
Averted and played straight in the same movie, Disney's adaptation of The Little Mermaid. Ursula turning Ariel into a human means Ariel needs to go fashion a dress out of some torn sails to cover up her human lower areas (she got to keep the seashells). When Triton re-turns her into a human she's given a sparkly blue dress, which shows that Titan's magic is much more gentle than Ursula's since he wants the best for her.
In the animated movie Monsters vs. Aliens, there is a very blatant example - Susan's wedding dress. She grows from normal size to nearly fifty feet, and the dress (with minor shredding of the skirt) manages to cover as much as a one-piece bathing suit would on her giant form. Never mind that the amount of fabric in the torn wedding dress on her giant form would make maybe thirty normal-sized wedding dresses. It could be Hand Waved by the dress absorbing some of the Quantonium, but obviously the real reason is that the movie couldn't have kept its PG rating otherwise.
A more justified example is the alien cat suit she wears after Gallaxar abducts her, which shrinks along with her as he drains the Quantonium from her body.
When Jack Skellington is shot down by the military in The Nightmare Before Christmas, his Sandy Claws outfit is shredded, but his tuxedo is completely unscathed. Also, at the beginning of the movie, when Jack rises out of the fountain, his bat-bow tie visibly straightens.
Completely averted (ultimately) in Pinocchio when Lampwick turns into a donkey. He retains all his clothes at first, with no damage to them except for a donkey's tail ripping through the seat of his pants. Once he's realized what's happened to him and starts to lose all remaining vestiges of his humanity, he panics and thrashes around so much that all his clothes fly off his body, leaving him naked and completing his degeneration into an animal.
In The Princess and the Frog, Tiana's dress doesn't change when she's turned into a frog. However, she does gain a dress when she becomes human.
Rock-A-Doodle first averts this where Edmund actually falls out of his clothes after being turned into a cat by the evil Duke of Owls, but later plays this straight when he changes back into a human at the end of the film; the reason why his human self now has clothes again is because as soon he was turned into a cat, he immediately discovers that unlike all the other animals in the film, who wear clothing, Edmund is actually naked and as a result he immediately puts on a large shirt, but no pants. But why is Edmund wearing pants after he got turned back into a human?
In Shrek 2, when Shrek takes the Happily Ever After potion, his old clothes become ridiculously baggy and he has to rob a passing noble for a new outfit... yet when the potion wears off, his stolen clothes transform into the old baggy clothes that he left behind in the forest!
Probably justified as the potion restores both Fiona and Shrek to their "pre-potion state". This is a magic potion, after all.
This continues a precedent from the first film, in which Fiona's dress always fits her, even when she transforms at sunrise or sunset.
Subverted in Wallace & Gromit: The Curse of the Were-Rabbit as Wallace's Y-fronts do survive the transformation sequence, as they are clearly shown to be intact when they fly into the face of Quartermaine. When Wallace reverts to human form, it leads to some funny Scenery Censor items.