match 1:
Simple things to work on: get a grab? PUNISH! you let him out freely once or twice which is bad, espeically at low %'s, cause you can get those nairs for that damage.
Sweetspot. Sweetspot. Sweetspot. G&W has a retardedly awesome edge grab range... one of the few things he has, makes playing marth sooooo much more possible, of course you'll wanna mix it up and go early so he doesn't just edgehog you the whole time.
Protect yourself on yoru way down, it can be hard against marf, but you've got a nice fair/bair if he gets close enough.
Be more aggressive, stay in his face.
Dtilt is ok for a little damage, but you can't follow it up very well from 70-whenever marf dies from it. However if you do pull it off around 70%, might as well up-b to get the extra 6% or so, it's basically free and he's safe either way.
Approach with some FH autocancels when marf is jumping around, or to bait him as you waveland.
match 3 - you should have let him falcon punch you for the lulz
if you're near a wall (like the tree) a lot of people will SDI into it so they can tech and not get hit with a nair, try throwing them away from the wall, when they DI towards you you can still hit them with the nair pretty well
I like the 3'rd stock ****
things to work on: When you're stuck near obstacles (i.e. tree, wall, rock/hard... slanted platform ****), attack according to how they're gonna approach. (dtilt doesn't work so well when C.F. comes from above) and when you have a grab, try to read where they're going to DI to punish better. Nice off stage work with the falcon this match.