I have heard that these ‘sidestyle’ tricks you are talking about would be called ‘Excaliburs’ (not sure about that one) or ‘vertical tricks’.
One of the easist things to get started is to learn to do Letter A, Which is this:
and then try to do it vertical. Hard to explain, but that’s how you can keep the yo-yo in a constant state of moving the easiest way.
It’s hard, but you can get it if you practice hard.
Go ahead!