Yep, DADdy's got some advice for you too, PK.
I know what you're talking about, what you describe above about loosing momentum and hitting a wall at some point in the match. I'm going to try to address this by kind of...stacking techniques/approaches/punishes/w/e into different categories. But first, an observation:
I can't tell you how many matches I've had where I literally just destroy my opponent for the first stock and a half or two stocks, but like you said, at some point I'll hit a wall and have difficulty finishing the job. I think the reason this happens is because 1) when an opponent goes up against a competitive level Ganon, they're not only confused as to how EXACTLY to fight him, but they're just kind of shocked. 2) As the match goes on and your opponent gets a feel for your spacing/play style, they will adapt (if they're good) and begin to seemingly "limit" your options. That is, baiting them with a DAir into a SS FSmash might have worked for one or even two stocks, but it's certainly not going to work for all three, let alone a second or third match. This is when you need to draw on memory and remember not only all your other kill options, but the specific nuances of your match-up (more on this later).
All-the-Time Moves (Use them all time)
- Thunderstorming
- Aerials as bait for buffered follow-ups (DAir, UAir especially, also BAir)
- UAir
- DTilt
- Jab
- USmash
These moves above I have listed under "All-the-Time" because you should, duh, be using them all the time, throughout all three matches. They are listed as such because they are moves you should not be afraid to spam/degrade their knockback on. These are not just your killing moves, they are also (and more importantly) your spacing moves. Your opponent should not be able to recognize that you only T-storm as an approach and only UAir as bait. These moves are all listed in the All-the-Time category because they inherently should be just as much about mindgames as they are about racking up damage. All of these moves can be followed up by buffered attacks. DTilt and iDA are by far the most important and common follow ups. Most of these moves can also be used as approach, bait, OR retreat, and the more options you have out of these moves, the better off you'll be and the more cautious your opponent will have to be. These are the moves that hold your spacing, and that's what wins the games.
Sometimes Moves (Use them sparingly or under specific conditions)
- FJ NAir
- Wiz Kick / Aerial Wiz Kick
- Gerudo / Aerial Gerudo
- DA/iDA
- Stage Spiking
- A well-spaced DJ FAir
The "Sometimes" moves are move that you can't be relying on to win the match, but should be kept at the ready for a variety of reasons. For instance, Wiz Kick is generally a pretty bad move to use at a competitive level unless you just can't wait to get grabbed. However, Wiz Kick is incredibly successful at catching overly aggressive characters off guard during their approach if you use it directly after a bait of some form. I, for one, use DA like there's no tomorrow. Ganon has one of the best DAs in the game, and usually I use it to rack up damage and get my opponent in the air for follow-ups. However, if I'm facing, say, a MK, I purposely don't use DA until I get them up to around 80%. Gerudo -> iDA = instant kill at about 90%. That's just disturbing. At a certain point you might realize you're having a h3ll of a time with Aerial approaches. A FJ NAir is often a safe way to start cutting back your approaching opponent. It's not incredibly consistent, but it at least makes your opponent realize that they can't just keep lobbing over the top safely. Gerudo's not going to be as helpful in high level play as it is vs your little bro. You need to read it's usage much more carefully or you'll get punished. Gerudo should be used to grab out of shield and to punish lag almost exclusively. Regarding stage spiking, if your opponent dares to stay on the ledge, and you just aren't confident in your ledge stomp, just run off the side and flick the c-stick up or back. A well timed UAir or BAir right out of invisibility frames will absolutely pummel an overzealous ledge hanger. BAir here is probably your most effective since UAir should be pretty stale almost the whole match. BAir is usually pretty fresh and can kill at ridiculously low percentages on the stage spike. Chars with god recovery like MK can still get killed at like 50% with a fresh BAir. I. LOVE. STAGE-SPIKING.
Hey! You-forgot-about-me! Moves (Having trouble killing? How about a nice FRESH Ftilt?)
- FTilt
- BAir
- Stage Spiking
- Gerudo -> iDA (char specific)
- Ledge Hop -> BAir/UAir on recovering foe
- DSmash
- A well spaced DJ FAir
- Do you have a release grab?
These are the moves that I go to when I am thinking, "hmm, DA, DAir, and DTilt are stale, FSmash and USmash are too slow, fighting over the ledge is too risky...what do I do?" How about baiting with a UAir or USmash directly into an FTilt? FTilt will almost always be fresh because it's just not that good for racking damage, but it's knockback is just insane. Think about BAir the same way as FTilt because, due to its...strange hitbox, you probably didn't connect with it too many times, so it's probably relatively fresh. If you hadn't noticed already that the char you're facing is guaranteed Gerudo -> iDA, smack yourself in the face and then grab that m f*cker and iDA him to h3ll. If you're doing a good job hitting your opponent off the sides but they keep getting back, run to the ledge and speedhug so they think you're incorrectly edge hogging them, and immediately jump off the ledge to meet them with a BAir, UAir or DAir. I use this kill ALL. THE. TIME. It lets Ganon jump way high up without having to rely on FoG. Finally, chances are your DSmash is only as staled as the number of incorrectly buffered iDAs and DTilts you did during the match. Look for an opportunity for an opponent rolling past you, and if you see it, flick that c-stick down for a DSmash. I don't like it, but it works (sometimes).
I know this is a lot of information, and it's hardly well organized, so I apologize. The gist of it is this:
ALWAYS thunderstorm, feign aerials/USmashes as bait, and DTilt/jab/UAir for spacing.
DON'T FORGET ABOUT FJ NAir, Gerudo/Aerial Gerudo and their follow ups, DA/iDA, Wiz Kick/Aerial Wiz Kick, DJ FAir, and Stage Spiking with BAir/UAir.
When having difficulty finishing the job,
RESORT TO baited FTilt, Stage Spiking, can you Gerudo -> iDA?, match-up specific techs (release grabs, for example), Ledge hop kills via BAir/UAir on recovering foes, DSmash.
Most importantly, you need to be using the tried and true ganon tactics - those listed in the ALWAYS category - even once your brain has moved into the proverbial "FTilt FTW!" mode. Once you whiff the FTilt once, your cover is blown, and they're going to be watching out for that terrifying spartan kick...I mean, who hasn't seen 300, right? As long as you're maintaining spacing as best you can, there's nothing wrong with racking up some extra damage while looking for the opening to get that kill. In other words, don't just rush in like an idiot with the first "fresh" idea that comes to your head towards the end of the match. Keep your cool and wait until you see the opportunity, IF you see the opportunity.
Christ, this is an ugly post. Sorry it's not better organized, but I promise there's a lot of good information in there somewhere. Good luck, dudes.