Whoa, Grand finals? I hope I'm qualified. I have some experience with Fox vs Samus but none recently. Still I think I have some sort of an idea about how it goes. I'll comment on the beginning of the second link you gave now(this became a bit long).
Don't up B stall if he's that close, you could have been punished. Just double jumping is safer and you can control your invis time better because you have full control over fastfalling and you can also delay more by wavelanding on the stage and so on if necessary. I personally would cut up B stalling altogether, I think it's obsolete for everything but showing off.
Uthrow instead of dthrowing. Even though you can't combo Samus is really vulnerable from below. If you're scared of the nair it's very easy to bait it out and after that you can punish her. Get used to the hit stun you have against the Samus and if your opponent likes mashing it out always bait it whenever they have the room to get the nair out. When they stop doing that you in turn can be more aggressive. Samus's options below her are bad, you can easily avoid bombs as well.
By the way, be more careful about pressuring her shield. You spaced your bairs well but even so up B has a surprising range. Just because your opponent hasn't really used it doesn't mean they won't.
Feel free to shield more often against Samus. She doesn't have great options against your shield and grabbing is a hugely high risk low reward move.
When Samus goes on a platform in preperation for a smash missile dropthrough, try dashing under her. It's amazing how effective that is. You might even get a free up tilt combo off.
Don't be too straightforward in your approaches against her, and rather spam running forward -> shield or such. You have no rush in this matchup, and her CCC and wavedash -> fsmash game is very strong. She's rather weak diagonally up in front of her, and doesn't have great options there, though. I actually would even try to just jump -> shine and double jump away. It's safe against CCC and wavedashing away and difficult to punish by her. Still, you don't really even need to approach her here. Your projectile game is superior to hers and she is very strong defensively but her offense is extremely weak. I'd play more patiently and, again, use shield far more often.
Well, you got stupidly hit by her charged B here. As you probably know, don't show off and do laggy stuff when she has it. you can react with shine, so play towards that. It's pretty simple to bait a B by an inexperienced Samus so give it a try, but still concentrate mainly on not lagging for long periods of time and doing just very safe things. Don't feel the need to approach her either, again.
Samus has good recovery, but here you had an option to shinespike her. Take note of her jumps and go on the ledge and abuse your invulnerability to shine through her up B. It moves pretty slow and it's not difficult to hit her out of it. When she's not in range to up B onto the stage she also is very vulnerable to shinespikes because she's so weak diagonally up/in front of her in the air, so feel free to jump for a shine spike. After you force her to recover higher you gain other options, namely up air for kills while bair basically resets the situation. Later on you shinespike-edgeguarded well, that's good.
Samus is still spamming dash attack and never grabbing, you should have caught onto shielding far more often by now. Remember it's at least a free up smash.
When Samus is recovering, spam Blaster. It's just a few % but it adds up, especially as she tends to take quite a while getting back onto the stage. It might also pressure your opponent into making worse decisions due to becoming impatient.
Use Shine far more often after aerials. You use it sometimes but there's numerous unsafe aerials that you do that really would get punished by at least up B. Even if you can't combo as well afterwards, don't worry about it. Being safe is far more important.
Only SHL when far away. If you SHL close to your opponent you're risking a huge punish for... 2%? It's not worth it at all. What I consider to be too close = if the opponent is in range to hit you with an attack before you land from your SHL.
By the way, when Samus is at low percentages try not to do early aerials while SHFFLing, she can CCC it easily. either aerial really later or just do fastfall fulljump aerials into shine. Still, against Samus I see absolutely no need to SHFFL at all when she's on the ground and at low %, so I'd just cut that out completely.
Your movement is also kind of poor, you should dash longer during dash dancing so it's actually useful for altering your spacing and avoiding attacks. Dashing in place is completely useless. You accomplish the same thing by just standing still.
Don't dair, almost at all. It's really easy to smash DI and punish. Off a shield you have so good options in usmash and grab that you really don't need risks.
If your opponent seems passive in shield, mix in shine -> grab. You can even do it after a bair if you learn to turn around before that. It's a very simple way to open your opponent up.
I also think you're far too straight-forward. Even though you won this game, when you wanted to attack you made it clear you were going to attack. When you didn't, that was clear as well. You didn't use shield often enough, you didn't shine enough, and you seemed too impatient in this matchup. You seem too impatient, and I think that you would be in big trouble against a patient player that just takes advantage of the openings you create. Fox really can play so that he only leaves the bare minimum of openings.
You also seem to waste time on useless things, like wavelanding on a platform for no reason and dropping down with a laser. That's not a mindgame, that's predictable, and a free punish. If you're far away from your opponent, you could instead get in another laser and have 2% more inflicted. Dash dancing like that far away from opponent is useless as well and wastes blaster time. It's obvious you aren't going to do much, you weren't even faking that you were going to approach. More lost blaster time. I also got the impression that you want to get up quickly and that charging a smash anticipating a tech in place would be profitable, and after you get hit by that you're going to techroll away. Might be just my imagination though.
