As far as I can tell Captain Falcon, Dedede, and Bowser have borderline solid (40-45 for Ganon) matchups vs. Ganon. While Ganon has several respectable (or should I say, disrespectful) yet effective moves with his aerials, smashes, and Flame Choke, the problems come with his speed. As Ganon’s the slowest among the bunch, Dedede and Bowser can deal with him via speed, range, projectiles (Gordos and Fire Breath), as well as having more potent offstage games. As Dedede has greater, disjointed range with his giant mallet, greater on and offstage games, as well as having more solid and consistent tools, Ganon will have trouble offstage and keeping up. Bowser is faster than Dedede, deals more damage, has a better recovery, and has more damaging aerials. While not as potent offstage as Dedede’s and Fire Breath not as effective keeping the Demon King out, they still work for the most part. Plus both the Koopa King and the penguin live longer as far as I know.
Captain Falcon generally has an easier time due to his speed and easier combos to land, but more caution will be needed if Ganons do rack up damage and read his plans. As Falcon’s moves are faster and more reliable to land, Ganon will have to play more defensively if he doesn’t want to be caught in combos.
Overall, while Ganon is not solidly countered (as he can quickly take out stocks if people aren’t careful), he does start out with disadvantages to Falcon, Dedede, and Bowser. I think it’s a soft counter for now (between 40-45 for Ganon) as the polarizing traits are remedied better and Ganon stands a better chance against them.