Coincidentally enough, I actually teamed with a DK at the past tournament. One thing we did often was have the DK cargo uthrow and then have me follow up with an aerial to finish them, or if they're lower (read: not kill) percent and I catch them with a flame choke, having DK follow up when I jab them afterwards. Other than that, it's mostly about playing your own 1v1 scenarios and helping each other out when being ledgeguarded or double teamed, that kind of thing. If the DK you're teaming with is good, you can rely on them to jank out one of your opponents with DI mixup cargo throws offstage, cargo throw stage spikes, etc. As Ganon, it's your job to be very skilled at wavelanding/movement in general so that you can have one of your very threatening hitboxes out wherever you need them to be in a short amount of time. If you have the presence Ganon should have, then that gives DK the space to kill people with jank.
Another thing, DK and Ganon have a lot of separate matchups that are good/bad for them, so make sure you have the right character vs whoever they're playing. For example, if they're playing G&W + Lucas, you'd want to be on Lucas and let DK have G&W. That kind of thing.
The other thing, stages. Ideally you'd want somewhere with a bunch of platforms and a ledge that allows for stagespiking, like Lylat (if legal in your region), Battlefield, and Skyworld (if legal).
Stages to avoid, I'd say FD and Distant Planet, among others.
Good luck!
