Can you put trapazoid frets on a guitar with dot frets?

if the neck fits in the joint absolutely , but make sure to intonate the guitar so the harmonics line up with the neck which is something big for experienced players, very easy to do. Tune the guitar...

The guitar capo.

It is not bad for the guitar, but the capo will be kind of useless as it won't be fretting the strings properly.

I think frets are on a guitar in order to make a tune and play different notes.

Frets define the length of a string to produce sound of a certain height. When pressing a string on a fret, the fret serves a barrier. The shorter a string is the higher note it produces.