A few words I want to put in since I play both Jigglypuff and Ganondorf more than any other character.
Quite frankly after playing both characters I would say this is a even matchup, 50:50 easily if not actually favouring Ganondorf slightly towards 60:40.
Jigglypuff has incredible aerial speed, DI and options there is no doubt. The Pound is an amazing setup/launcher move, approach with its priority and knockback. Puff once let into Ganon's personal space can wreak all kinds of havoc crawling all over him and if Ganon is sent off the stage its game over. Jigglypuff has a far easier time chasing most characters off the stage than even Metaknight due to his raw aerial speed.
Most people make a severe mistake thinking Puff has a non-existant ground game. His grab game alone is better than every other ground option he has, only better ones being a iDA which has considerable knockback and speed. NAir is disgusting sometimes with its extended hitbox good knockback and practically instant startup time.
However it should be noted that once ou connect a Flame Choke on Puff he is never, ever getting away from you. Puff's roll and getup attack is terrible, predictable and short ranged to a good tech chasing Ganon. Seriously when I see Puff on the ground I can tech chase the poor thing all day long till I get as much damage as I like on him.
However theres one thing I also learnt, if Ganondorf's hits are like a bus full of fat people to most other characters. To Jigglypuff its like being struck by a meteor hurtling through the atmosphere at several thousand miles per hour. First off is UAir is a horribly punishing move, it outranges all of Puff's options in the air.
Ganon's BAir intercepts Puff's SH moves quite sufficiently, Puff's Pound has a certain blind spot where after the initial hitbox the BAir can easily outpriotize the remaining hitbox. Actually if you're even lucky enough to connect with a fresh one near the ledge, I've seen it KO Puff at only 55% on smaller stages. Aerial Wizkick is the single biggest killer of Jigglypuff who thinks he has control of the air its huge priority and hitbox and early kill (60-70%).
Here is a raw fact, Ganon's DA completely flattens Puff, absolutely destroys him. This is a lethal killing move and it will kill Puff extremely extremely early, even the Pound's freakish priority cannot stop him getting run over. Also one of the msot important things to remember when fighting Puff is the first few seconds are important. Out of Puff's moves he does not have a single move besides Pound and his grab which have enough knockback to stun Ganon longer than it takes him to finish the move. It means you are guaranteed a hit almost straight off the mark if you watch out for those two moves.
DAir -> Rest will not kill Ganondorf until extremely late percentages where quite frankly it'd be easier to kill him by just BAir or FAir'ing Ganon off the stage. Nevertheless DrillRest is quite easy to pull off on Ganondorf but actually connecting with it is a whole different matter.
Either way whilst Puff has an awful lot of options on Ganon in the end Ganon's raw power and weight actually gives him a major advantage which actually re-balances the scale.
