Your neutral game is way too predictable. Randomly throwing out nairs on shield is not what yl is about because you're getting punished every single time for it. Your friend is waiting for you to do something to him that he can punish. Neutral is all about that and you're losing it hard by being the aggressor. YL is not built as an aggressor and I know it may sound lame but part of his meta is camping for opportunities to get in. If things don't look like their going your way and both of you are just hit each other's sheild, reset the neutral. Get away from him. So think actively and use your movement options.
Falco's game is movement based. Counter that with yl movement. He's faster than falco and has more stage covering options (bomb boomerang) to utilize within that speed so take advantage of that.
Dair is never a good option below 70%. Upair is a combo starter. Never use it when it's just a wild guess.
I'm sure you know this but bomb dair is yl's bread and butter. Keep it in your arsenal at all times. But don't spam it.
