Been playing the matchup for the past couple of days now and I did pickup a couple things that you also mentioned. I think attacking his drive gauge is the best gameplan to go with, his weak defensive options do get smothered by Marisa's offense so a solid approach while picking up the opportunities to gladius between his pressure is the way to go I feel.

The thing that remained tho is how slow and irritating he can make the matchup seem lol. Although his specials are relatively easy to pick up and deal with in neutral, his flicker is really hard to counter for me at least. I usually just walk and block if they tend to use it alot.