I think what Twinkles says pretty much hits the spot. Too add onto what he said:
First, I think it would be good to practice spacing with Falco's lazers. True, Falco's lazers are a good approaching option, but they're also a very good spacing option against Marth—something that you needed to use in the matches. If you flick the joystick the opposite direction, let go of it, and press B right after, Falco's will change his direction when shooting his lazers. It's faster and more convenient than rolling or running toward the opponent to get Falco to face the right way. Second, you seem to struggle following up with Falco. One of Falco's greatest strengths is his D-air, not just as a gimp, but it can start many combos. You seemed to use your N-air to try to start a combo, but I find N-air to be more for stage control when the opponent is in the center of the stage. D-air puts the opponent in a compromised position if you can L-cancel out of it, and you can use your U-tilt or Shine, then follow up with another D-air, etc. It would be a good idea to practice short-hopped D-airs. It's not as effective on Marth to do short-hopped D-airs, because of the horizontal priority he has with his sword, but it can be effective on other characters. Either tech chase off the D-air after following up with a down throw and maybe a jab reset, or try the follow up I mentioned above if possible. Third, waveshining isn't as necessary with Falco as it is with Fox, but it's always a good option to have when you miss the Shine—or it gets shielded—and need to get out of it. There's a waveshining guide in the Falco Character Discussion forum if you don't know how. Also, I think using Falco's shine in the air is purposeless, especially against Marth, because of the direction of knockback. When Fox uses it in the air, it puts the opponent in a compromised position, because it hits the opponent forward, but when Falco uses it in the air, it hits the opponent upward, which isn't really a compromised position that Falco can take much advantage of. IMO Falco's shine is much better used on the ground when you can follow up with a D-air or a B-air for KO's. In such scenarios where you used Falco's shine in the air, I would either just use a proper aerial, or focus on spacing so you can properly punish, let's say, Marth fast falling with a D-air. Like Twinkles said, execution needs to be a second thought when using Falco so you can focus on your opponent instead, but I also think the path to making execution a second thought not just lies in tech skill, but understanding the mechanics of the character in general.
