It seems that there are different sizes and types of mouthpiece, and that they are considered to be better for different types of music.
It seems Trombone Champ is not as faithful a simulation of the art form as one would hope.
I kid the trombonists, because I don’t think anyone picks up that instrument unless they have a sense of humor. The problems involved in buying a new mouthpiece are not limited to just the trombone, or even just to the brass section. It seems merchants are generally hostile to the idea of letting you “try out” any product that you stick in, or on, your mouth.
I used to have similar qualms when I rode motorcycles. The showrooms always weirded me out.
“Hello my good man. I understand the new models for this year are in. Excellent. Point me to them, so that I may straddle them. Yes! I shall straddle each and every one of them. Then, I shall not buy any of them. But every time I see one of your company's fine motorcycles on the street, I shall look at the rider and secretly wonder if he or she paid full price for one of the bikes I straddled, and that will satisfy me more than any two-wheeled conveyance ever could.”