No idea. The priority on her moves, as well as Luma's, have insane priority and come out incredibly fast. I'm trying out strategies myself, including dashing in with Rock Smash, jumping in with Nair, etc. Can't say anything for sure quite yet.
I like playing more defensively. You can abuse Charizard's multi jump to bait out Luma and Rock Smash can be a very powerful tool for getting in on Rosalina, especially if you master reversing it to catch her rolls.
I feel like Flamethrower is a really good tool for racking up that damage. Getting the kill can be a little hard, but Charizard's Bair and Fsmash can be good for this. Flare Blitzing around haphazardly isn't going to get you anywhere, but if you get rid of Luma, or Between Luma and Rosalina it's a very good way to deal with Rosalina's insane disappearing rolls.
I like using retreating Nairs to deal some damage to Luma without getting caught in a jab. Starbits is annoying, but you can muscle through with Rock Smash.
Can you please elaborate on this? Every single time I face a (good) Little Mac on For Glory I get absolutely stomped as Zard. The second I'm launched into the air he just keeps juggling me with those smashes and up tilts. Rock Smash's super armor frames are useless when Little Mac's own smashes have super armor too!
He's also able to punish the tiniest ammount of lag with all that speed, which also spells trouble for Charizard.
You just have to time the Super Armor better than he does. Don't just go in for the Rock Smash, time it so the super armor eats the smash. Charizard's multi jumps also makes it pretty hard for Mac to juggle him. Flame Thrower is also amazing. Jump and angle it down. You'll interrupt so many things. And Flare Blitz is great for punishing over rolling and recovering to the far side. Throws are your friend. Charizard can toss pretty far even at low percentages.
Watch out for counters though. Getting kill moves can be tough because of how good Mac's counter is.
The problem is when King Dedede uses his Gordos when Charizard is approaching him. For example, a Firebreath won't work because Gordos go right through it, and King Dedede often throws a Gordo at Charizard when the the Flame Pokémon is just about to reach him and grab him or hit with a Neutral Air. Charizard cannot react in time to hit the Gordo back in such a situation. How do you approach King Dedede with Charizard?
I'd say you don't really approach Dedede, but when you do Rock Smash is your friend. I like using retreating Nairs to whack his gordos back because short hop Nair is pretty much lagless, so you can power shield if he hits it back. The idea is to wait out his patience.