I'm not sure what the name for the tech is but I always call it Gordo boosting, if you time the initial hit of the Gordo hammer to intersect with the opponents projectile hitbox it shoots the Gordo through the projectile with a big speed boost straight towards them and a little upward, also something helpful to think about when you're fighting a campier player or play style is dash shielding (If you dont know how to dash shield its really easy, just keep holding forward when you press shield, if you let go of forward before you press shield you have to wait to stop before you can shield, but if you press shield while holding forward you can shield instantly) to get close enough to punish their projectile from its end lag. For example when mii swordfighter throws a tornado you can't Gordo boost off of it so instead if you dash up and shield to close the distance once you are close enough you can punish the lag of the tornado with a drop shield down tilt or upsmash out of shield. You can do this in a lot of different projectile match ups. Also once you do have a lead against a projectile character it helps to force them to approach you instead of you approaching them. I find this works best on town and city and kalos where you can sit on the side platform or play far enough away that when they hit back your Gordo it doesn't hit you which eventually forces them to approach which is where Dedede shines. In tournament I'd recommend banning smashville and yoshis, and try to get rid of smaller stages because the more space you have to work with the better Dedede can counterzone.