Hylian, my best advice for falco is mostly keeping the right frame of mind. Don't become "afraid" when you're falco; a problem I used to have with him is when I get locked into making dumb mistakes because falco falls prey to lagless characters like MK and G&W. When you're falco, you really gotta step back and reassess the situation if you keep falling for the same dumb things because they are pretty fast. Approach with lasers whenever you can, because even if it doesn't hit the opponent it still limits their movement. Take advantage of a missed smash with your fsmash. SH immediate phantasm as an approach on any character, there's no lag and you can chain them together at low percentages. Reflector when your opponent is on the end of the match and you are trying to edge guard, and when ledge guarding specifically, ledgehop bair at the VERY last moment. Bair has so little startup lag that it is efficiently surprising.
Now, on the problem of MK and G&W:
For MK, sh dair, shff nair, chaingrab, phantasm. These are things you should really stick to with him. Don't try and confront him from the front in the air or below, because his fair and dair are both very fast. His whorenado is easily destroyed by a simple laser or reflector (or dair in the top of the tornado, but that's a bit harder to get). When he is recovering, remember that dair has equal priority to MK's shuttle loop. Both shuttle loop hits. Use that to your advantage.
For G&W, spot dodge his dsmash and counter with a simple jab combo. If he starts a dthrow dsmash chain, tech roll away and jump the hell away from there. If he dairs from above, spot dodge and usmash or dsmash. Alternatively, you could grab. I don't remember if you can do a real chaingrab with G&W or not, but I'm pretty you can. Fake out G&W as much as you can with missed SHDLs, and then SH immediate phantasm into him to toss him up. SH dair is effective, but if he counters with a utilt or sh uair, well... watch out for those.
Falco is a good character if you know how to use him, just uh... I guess watch how sethlon plays? He's the nearest good falco for you, and he's better than most falcos I know so just observe really. Good luck learning the blue bird himself.
.
