Fantastic advice against both characters is to avoid being above them.
Don't know much about Puff except dthrow -> stuff (i heard puff can rest out of dthrow -> knee around 40-50% for whatever reason though). Uair and bair are probably your go-to spacing moves. Stomp is high reward if you can get one off (especially if you somehow catch her in the air, cuz her wakeup/tech options are ****).
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Marth is about getting in that sword range then making him feel very uncomfortable. Basic approaches with nair, knee, or whatever floats your boat, just do your best to not get grabbed because getting grabbed on either side of this matchup sucks. Once you get a grab, dthrow combos into itself until like 10-20% if they don't DI down and away (if they do, it's a tech-chase), uthrow can lead to a nair (dunno exact percents, under 30% though), and uthrow -> uair starts working around 30% iirc.
uthrow -> knee works around 60-90% give or take certain DIs. dthrow -> knee generally only works if they DI in or they DI offstage and not into somewhere they can tech.
side-b can catch marth out of aerials and sloppy dash dances. leads to lots of uairs at low-mid percents. pretty good.
once you get that first hit in, just whatever it takes to hit that mofo unless you know nothing's gonna work. marth's pretty squishy, so they'll feel any hit they take.
EDIT: If what I'm saying's wrong, someone's bound to correct me sooner or later lol