Having flashbacks to International Track and Field GBC (played the heck out of that story mode before I got Mario Tennis -- it let you have a girlfriend! Two of them, even! And then your friend would tell you that you shouldn't do that, but there were never any negative consequences! Best game ever!) and Gracie's car in Animal Crossing (never got that, even with a turbo controller).
One technique I got a bit of use out of when I was going for the Golden Racket in Mario Tennis was to put my hand inside my shirt and rub my knuckle back and forth on the button through the cloth, though the efficacy of this can depend on the specific controller. I only ever got the Silver Racket, though, so yeah.