Why does text that can fit in one line take up two?

Question

Instead of displaying
BUTTERFREE used Tackle!
it displays
BUTTERFREE used
Tackle!
Other kinds of test, like "It does not affect BUTTERFREE..." only take up one line.
I only know that it's true up to Gen 4. I haven't played any newer generations.

Answer 1

This is because they want to give distinction to the move that Pokemon used. Following your example, Tackle is the move Butterfree used, and to make it immediately visible to the player, it's placed on the next line. It stands out and is emphasized over the other words.
Other lines that do not contain any such feature they want to emphasize, such as "It does not affect Butterfree..." do not need a line break.

Hope I helped!