His aerials aren't nearly as safe as they were in Melee or Brawl, so just shield them and punish accordingly (jab or grab in most cases). His landing lags are also slightly worse than they look.
Though shielding aerials is often a good idea, remember he can neutralB your shield away. Regarding aerial marth again, Zard's utilt and usmash all outrange anything Marth may have in the air (and can't even get countered with decent spacing).
Now, as far as grounded fights go, his sideB can punish too many charizard things and does very solid damage, and his tilts have all very decent disjointed range, limiting Charizard's main keep-away uses of dtilt and ftilt. Flamethrower is a decent walling option in the ground, and he isn't quick enough to jump and punish, so use short bursts of neutralB while he can't reach you.
Remember that Marth is light and a tad floaty, so uthrow nets early kills, and dthrow stops comboing reliably early as well.
I'm still tempted to try reverse aerial rock smash facing the ledge as an edgeguarding tool against Marth.