Also just going to critique the Robin--
The Robin/Luigi MU is in Robin's favor as long as you keep Luigi out and avoid putting yourself in situation where you can get grabbed. Be wary of offstage play as Luigi can gimp you, but vice versa is also true.
0:06 You tried to space a fair which was nice. The problem is you approached with LSFair (not safe on shield that close) and it didn't autocancel because you input fast-fall (Luigi punished your landing lag). Better options include autocancelling fair into jab, or using your second jump to escape towards the center of the stage (perhaps along with a spaced landing LSBair).
0:07 Once you get hit by Luigi's fair, the best option is to nair. You can't airdodge or else you get caught. Nair is your fastest aerial that may just clank or trade with Luigi to get you out. Otherwise, be prepared to eat the string and have to reset neutral. Since it's low percent, using the second jump might not be a bad option.
0:09 You use your second jump but not at an optimal time (too late to escape Luigi, too early to mix-up landing). Using it that high up in the air leaves Elwind as your only landing mix-up apart from falling and shielding (with or without fast-fall).
0:10-0:15 Interesting choice to jump around, but I don't see fast-falling which makes your landing predictable had Luigi decided to jump and nair at any point. You could have also spaced a Levin aerial while you were jumping about. The Levin Sword is much safer on shield if spaced than Robin's nair.
0:15 No need to get away. Just charge Thunder. If Luigi flies toward you, shield and punish.
0:19 Nice retreating autocanceled LSFair, but you aren't taking advantage of Robin's frame trap by following up with jab 1 to psuedo-hit confirm.
0:21 Nice jump away, but a poorly spaced Arcfire causes you to get punished.
0:24 You use your double jump but don't DI away from Luigi at all, and frame trap yourself in a nair that doesn't hit, allowing Luigi to extend his punish.
0:27 Robin won't always have enough time to jump away with a Levin aerial from bad situations. Rolling or spot-dodging are good OOS options to counteract an expected offense--and you haven't done much of it so I don't think the opponent would read it. Spacing jab 1 is also a decent option out of a shield drop.
0:29 I agree with what PotatoFoSho said--you should've used the stage to guide Elwind, reducing the chances that Luigi can gimp you.
0:45-0:54 Good choices for the most part.
0:55 The tactic that you're doing--charge canceling with jump into LSFair--is mostly to counteract approaches. You could've been more aggressive by juggling Luigi/cover landing options rather than passively charging Thunder.
1:00 Same idea--you're pretty safe with Elwind while Luigi has to recover. Some Elwind harassment/spike would've been very safe, especially since Luigi was throwing Fireballs.
1:06 Robin's pivot ftilt is meant to give you room to reset neutral. The first one didn't hit which was fine; now you can short-hop back and start out-zoning Luigi again. The problem was you did a second one in the same spot, allowing Luigi to move around you and grab.
1:14 Again, you have the advantage. Luigi's in the air. Everything he has loses to the Levin Sword as long as it's spaced properly. Since you didn't chase, Luigi has room to reset neutral.
1:18 Decent LSFair, just needed to be spaced better. Also good Nosferatu punish at 1:22.
1:26 Nice try, but sometimes it's better not to close the gap that you need. You also try to fsmash after the bronze fair, which just isn't safe.
1:43 Your recovery was too linear. When you use your second jump offstage, space a Levin aerial to get Luigi off, or airdodge (sparingly). You can even jump, fast fall, then Elwind. You don't just have to jump and Elwind.
I see a lot of tunnel vision. You get fixated on what you want to do next, but don't have a follow-up plan. Like charging thunder to LSFair wasn't working out super well, but you kept trying it. Or when you recover, it's always jump + Elwind straight to the ledge. Even when you have the advantage, you get fixated on what you want to do at that moment rather than considering what would be best to push your advantage, or stop your opponent.