You can jump on top of one of the animals at the end of the second Nina level (after beating N-Gin) to skip the requirement to transform 25 animals. Position yourself in one of the corners below the ledge your aiming to reach and then just jump on one of the animals to get launched up just high enough to reach the ledge. Going to the end of this section just ends the level immediately. If done correctly, this has the potential to save ~10 seconds.

NOTE: If both of the animals on that surface rush down on you as you're making your way to/past them, they can no longer get back up and you'd have to either death-abuse, backtrack and transform 25 enemies after all, or reset the run.

A demnostration of the skip can be found in my run here (watch from 38:30 onwards):