A lot of the neutral is just trying not to get engaged on. Charizard's neutral is sub par, but SH Flamethrower, B Reversed Flamethrower, jab, tilts (ftilt is really strong against Luma bc it deals just enough percent to knock luma into tumble) and SH Fair and Nair are probably the only viable neutral options. Just note that fair and nair need to be buffered in the short hop frames to auto cancel.
Main things you want to AVOID doing are Flare Blitz (I'll get more on this later) and Bair/Dair. Bair and Dair are really obvious because they don't autocancel, are unsafe on shield, and are for the most part easily punishable (maybe luigi doesn't get punished by bair on shield due to his ice physics. haven't tested). Aside from those though, don't spam random smashes because they're obviously not safe. Only smash attack that could probably be used is up smash because it comes out on frame 6 against aerial opponents and 7 against grounded, so its pretty fast.
Now for rock smash and flare blitz. Every zard player seems to use these moves differently. With Rock Smash, I like to play it defensively against combos, but its really solid on shield because of the damage and the possibility of getting a shield poke. The only risk is that if you don't get the shield poke, you're going to get grabbed, making it not as good. However, characters that try to roll or spotdodge will get caught with the pebbles. Rock Smash is also a powerful kill move; however, due the the pebbles being erratic at times, you might not get the kill because in the middle of the strong knockback a pebble will hit and take away the kill. Not really good if you're trying to get a kill, but if your opponent goes in for a dash attack or an aerial, you can catch them with the frame 5 super armor and get some solid armor. I've heard people have gotten up to 30% from rock smash alone.
Flare Blitz is much more binary though. It has heavy armor on the entire move and solid knockback, but its VERY unsafe on shield, and you will usually get punished. However, there are a few situations where I find it useful. If your opponent has expended all of their jumps and are slowly falling to the ground on the other side of the stage, you can read their movement and go for the flare blitz as a punish. This puts your opponents into a state of panic, and you can catch a lot of panic air dodges into the ground to get the guranteed hit. Other than that, there are some projectiles you can armor through, but due to the way Flare Blitz works, there are a lot of projectiles you think you can armor through and end up being unable. Just remember that the heavy armor can armor up to 14% of damage from most moves/projectiles.
Fly is okay OOS if you don't want to go for grab > up throw but the horizontal range on the move is pretty weak. It'd be best to do it in a situation where they're going to expand their hurtbox into you (say, a dash attack or ftilt for example).
I personally recommend remembering at least the rough numbers on up throw's killing. I created
this thread literally a few seconds ago because I realized 1.0.6 change list rolled off front page. Remember though, this was tested on FD in training mode and percentages can vary based off of positioning, opponents DI, and rage. A little (untested) thing I've noticed is that 50% on you usually equates to about 10% off of the kill % needed for up throw. Those numbers are just untested, rough estimates through gameplay.
This thread also has a lot of combos and frame traps that Zard can pull off against different weight classes.
If you need any help, feel free to ask in this thread if you don't mind waiting, or the Zard Skype Group if you need faster answers. Fair warning though, the skype group rarely talks about Charizard.
