Hmmm...
Stop jumping into the ****, especially against Marth. He needs to either stay safely at a distance with blizzards/IBs/ariels, or he needs to get in close with tilts/grabs. You had him zoned at that in-between range and he got tippered a lot.
As ICs, I've learned to slightly tilt my shield up because many people will jump a lot to avoid being grabbed, which results in high(er) hitting attacks. He got poked out of his shield repeatedly by Marth's fair because of this.
He should have better grab setups... especially against Marth. ICs can camp/desynch on Marth all day due to his lack of a projectile. Desynchs lead to grabs which should be a stock loss for Marth.
Is this the guy that used the wii chuck? If so, STOP. The wii chuck is a pain in the ***, especially for the ICs and their grab game.
It also didn't help that you know the matchup probably better than any Marth I've played. I think I could take ya though. xD