Ganon can actually chain grab fastfallers. On fox the cg goes to about 50%, except if they DI behind you can regrab them until like 70. At 0, just regrab if they DI in front, or turn and grab if they don't DI or DI behind you. Once the grab puts Fox at 21%, always dash back, and if they DI back simply regrab, if they DI forward, dash dance back and regrab, if they don't DI reverse grab. If they try to take this CG to the edge you can just stomp them when they DI in front of you, or continue the CG if they DI behind you. If they're smart and don't take it to the edge you can just fair them out of the throw once the cg ends and then try to follow up with a kill. Most platforms will interrupt this but you should probably be able to hit them with any aerial if they go onto a platform. Fox is still really hard to grab, though, so the matchup might still be in his favor.
I know the same thing works against Falco, Wolf and Captain Falcon, but I'm not sure at what percent it ends. Also, I got this off against a Marth recently, but I would think Marth can probably upb out of it, so I don't think it works on Marth except maybe one regrab at like 0. Although, I think you can get regrabs on most characters if they DI incorrectly, except for the really floaty characters. Also, you can pretty much always sweet spot a fair out of a downthrow once they are at killing percentages, no matter what character you're playing.
I've tested the cg on Fox pretty extensively, it seems like if you grab him you only need to get one read after the CG to kill him.