Are some pitches actually dangerous to throw?
Do certain grips increase your chance of arm injury?
To begin with the overhead throwing motion is not “good” for your arm. Our arms were made to work in an underhand (more fast pitch-like) motion. There are many things that can go wrong for pitchers and their arms. Quite a bit of the ability to stay injury free has to do with genetics. The rest has to do with your mechanics and proper usage of your arm.
Having said that, sure, there are different pitches that have potential of putting more strain on the elbow than others. The slider is tougher on the elbow as compared to a curveball – assuming they are both thrown correctly.
I’d rather not discourage you from experimenting with different baseball pitches. Instead, I want you to understand that most injuries don’t occur because of the grip itself, but the wrist and forearm angles (along with poor mechanics).
To illustrate this point further, here is a video for you.