Regardless, I'm not here to address whether you think I'm bad or not, I'm just curious though how you consider dtilt, bair, upsmash, jab, or full hop fairs (cause let's be real I didn't do much else) bad moves? How do you use Game and Watch if not at least using those?
Dtilt in specific is a very bad move in this game because of its massive amount of endlag. Your intention with this video seems to be to highlight that if Little Mac does his side B, you can force him into the odd windbox on this move to shoot him offstage. While interesting, this is hugely impractical because no one who plays LM seriously is going to aggressively throw out side B against you; it's a very high risk approach with minimal payoff and is only really usable as a mixup. LM players who know what they are doing are going to zone you on the ground with ftilt and dtilt, not spam side B and dash attack.
I could write paragraphs about how you could improve your playstyle generally, but it's easier to tell you a little trick to set you on the right path. When you are playing an LM player on For Glory who is bad (that is, the situation is the same one as in your video), you can guarantee a kill right off the start by waiting for the dash attack, shielding it into dthrow>nair (angle the nair so that he goes behind you), then quickly jumping up for bair>bair/ up B.
PS: try spacing fair from short hop, not full hop. This transforms a predictable aerial approach into real pressure.