Dragon Ball: Daima (Werewolf Reversion)

Thanks to Wolfy for finding this reversion scene from episode 9. Scroll to 06:50.

Digimon Ghost Game (Demon Transformation/Reversion & Size Growth)

Episode 39 ("Contagion Island") involves a little monster who likes infecting people. This makes him grow bigger and turns his victims into demons (they look like "Gyuki" yokai). The main transformation in this episode involved a female character, but thankfully there was a male reversion scene. In this clip it's preceded by the infection scene and the monster's size growth.

Victor and Valentino (Partial Insect Reversion)

In season 2, Episode 12, the brothers shrink down and end up in an ant hill, where they encounter an ant who turns out to have a face of an old acquaintance...

RE:Zero 23 (Weretiger transformation and Reversion)

In episode 23, Garfiel is fighting his enemies with only a gauntlet. He transforms to kill the Demon Beast in spectacular fashion, but not without exhaustion:

Legend of the Dragon (Werewolf Transformation and Reversion)

Thanks to metabee17 from our Discord server for finding these scenes from episode 22. A scientist has used a formula to transform himself into a werewolf (17:00):

 But he can only stay that way if his collar is on (19:13):

 

The Idhun Chronicles (Werewolf Transformation and Reversion)

Welcome to the winter update! Make yourself warm by cuddling up to all the werewolves and other beasties we've gathered for you. We hope you enjoy all 14 new items. 

Here is a clip from season 2, episode 2 of the Spanish-made anime The Idhun Chronicles. Prince Aslan, who contracted lycanthropy the last season, is chained up before he transforms into a werewolf. But the chains don't hold, so his comrade must hold off Aslan until he returns to normal:

Since we see his face change only during during the reversion (and that happens very quickly), we've included a screengrab of the process:

Don't Starve Together (Beaver, Demon, and Reversion transformation)

Kumaguma here with some transformations from the animated short Don't Starve Together: Tree's a Crowd, which is based on the survival game. In the clip below Woodie is attacked by a living tree and tries to fight it by shapeshifting. The first transformation happens at 00:17, where he changes into a werebeaver. At 00:43, he reverts from his were-goose form, and after being beaten as a were-moose, he then reverts back 1:15.




Another short, Don't Starve Together: Possessions, shows the origin of the imp Wortox. After angering Krampus he ends up manifesting a curse which absorbs Krampus (at 01:25). This possession causes the imp to become redder and grow bigger horns and a fuzzier tail.