Submitting a summary... Hopefully it's comprehensive enough. If it's much too long, let me know.
"Who is This?
Charizard, as many of you reading this may know, is a fairly heavy character. An adaptable character, with decent, ranged spacing options on the ground and air alike, ways to shake his enemy off him if he gets overwhelmed, and the mobility/aerials to become more aggressive once he's gotten a hold over the stage... He's a punisher: Add his three jumps, above average recovery with Flare Blitz and Fly, ability to gimp with the standard Flamethrower, and variety of specials to change up his strategy? While not exactly the best character, in the right hands, he can be deadly.
However, Charizard often has trouble with other defensive characters, or ones that can simply rush his defenses down. His shield and good grab range can help to mitigate this, but in some cases, his attacks can just be too slow to respond based on reaction alone. It doesn't help that some of his options can be fairly obvious, such as Flare Blitz, a falling Rock Smash... If you can find out what Charizard is doing to punish you, without him adapting, you've almost already won the game.
How does he relate to Charizard?
Refer to the above. Since this is a mirror match, it'll mostly come down to skill, knowledge of the character, and how well you can predict what the other player will do.
Approaching -
Here, your shield is one of your best friends. Neither of your attacks are really safe on shield, not causing enough knockback to slide him away, or having enough range. Really, only Flamethrower or a well-spaced N-Air are consistently safe. This makes Charizard's shieldgrab even more useful against any of their aerials and Rock Smash.
Rolling shouldn't be considered. With the threat of Flare Blitz (or really any Side-B) and Charizard's fast speed allowing him to simply dash grab/attack you if you choose to do this, it'll hurt you whether you roll away or towards them. You cannot let yourself get grabbed under any circumstances. Usually, your jab stops this. So will F-Tilt, D-Tilt, and Flamethrower from a distance.
It isn't really recommended to try and combat them from the air, considering that it makes your actions fairly predictable from then on. N-Air can be used for spacing, however, it's punishable on shield; Same with the other aerials. Usually, the aggressor here, as well as on the ground, is at a disadvantage. If you have more of the stage to fall back on, though, they become more useful for being aggressive.
Remember, Charizard is a punisher. Considering that many of his own moves are laggy and punishable if they miss, like F-Air, B-Air, Rock Smash, if you can bait them out and respond with your own (like F-Tilt, another aerial, or a simple grab) you can gain control of the stage, with more room to space them out. In particular, if you block a Flare Blitz... Don't Flare Blitz them back. That's dumb. Just run up and quickly U-Smash them.
Speaking of Flare Blitz... Use this move very sparingly. Trick them into thinking you only use it for recovery by sweetspotting the ledge, or moving to another spot on the stage above them. Purposefully ignore it. Be patient, even if you're a giant lizard dragon, and use it when they absolutely don't expect it.
Tips -
Watch out for Rock Smash if you're the one doing the juggling, as you can start the process over if they botch it. Charizard doesn't have options for landing right next to the opponent, but Flare Blitz can help him escape in the air.
Flare Blitz, on start-up, can be punished if you react quickly. A B-Air could end the match in style if you react quickly enough.
If you notice the other Charizard is abusing their Flamethrower, and you're in the air, move above them and Rock Smash. With Flamethrower, it's a very useful tool for stopping rushes; Say, if you're at the end of the stage and don't want to get knocked off. It can also be useful for edgeguarding Charizard, but Flare Blitz and Fly can make this fairly dangerous. Charizard will most likely not be gimped by any of your attacks on-stage; It's at this point where you can easily kill with attacks like your B-Air and Smash Attacks. U-Throw is also a safe, reliable option to kill with.
Overall, though, it isn't recommended to try and heavily edgeguard Charizard. While he's a large target, it can be difficult to get past Fly, Flare Blitz, and his extra jumps, all of which can allow him to attack.
Another important note: Rage. While you most definitely don't want to get your percents higher than necessary, it's important to consider the enemy's rage and your own. As Charizard has such heavy attacks, the knockback increase definitely benefits him. Add his ability to recover in both directions, durability to trade hits, and general defensive options, this can allow for surprisingly early kills. Just make sure you respect your opponent when he has it... Often, it's after one of you has lost a stock that the other has rage, not the reverse.
Stage options: Refer to this!
http://smashboards.com/threads/charizard-matchup-discussion-mirror-matches.407885/#post-19524606
Customs: As Dragon Rush is less risky, and Charizard doesn't have any projectiles worth worrying about, this seems like a more logical choice."
Is the format good? Was it too long and not good for visitors to the threads? I hope that these threads can be useful to people just looking into specific match-ups, instead of being short and to the point, like guidelines. Any suggestions that could be followed to make this better, or a revision entirely, would make me happy.