Stick to Fox. Your marth is horrendous. some feedback:
1. you block. why? you have a broken dashdance and a wall of sword. marth has no reason to block ever except maybe vs falco.
2. you play like marth has no range. you frequently hit with marth's hands instead of his sword.
3. you spam nair which is easily shield grabbed. not only do you spam nair, you overextend into the opponents shield to avoid any work put forth timing a dashgrab. if you're going to nair, don't overextend, do it infrequently, and dash away or sidestep upon landing. or really just don't do it. marth has la on his moves and none of them stay out so you can't afford to miss anything ever.
4. you don't use any trapping methods. marth is dumb because he can easily get you into a situation where you're already dead. the only one attempted in the videos is up B spamming hax's falcon (0:37-0:46) which was set up by him being ******** and not even you.
5. you're not using upthrow. upthrow is another major reason marth is stupid. marth can upthrow and suddenly the opposing character loses every method to beat him.
try this: base your ENTIRE gameplay around DD grab. like really thats it. don't block, and if they're dashdancing back run extra far and dtilt instead, otherwise just grab. if they jump at you, jump up or away and fair whatever they're overextending with. basically just grab or if they jump at you fair to grab. upon grab, if fastfaller at/close to the edge, and facing in towards the stage, downthrow. if they can fall off, react. if not, do m2k's lock of dthrow turn dtilt. otherwise vs any other character anywhere else, upthrow. then do moves at them until they die such that they can't land. you don't care about kill moves because they're still helpless. just focus your entire style around DD grab or fair > grab and upthrow them and never let them land. don't fall for any tricks and never overextend. you'll probably do substantially better than you are now. if you don't know what to do after upthrow, fair.
edit: if you want to edge guard CF, just dtilt. CF's body box always goes over the stage so you can always dtilt him unless he comes up backwards. if he comes up backwards, WD FF edgehog him. if he techs the dtilt, dtilt again and keep doing it until he dies. he can literally do nothing about it.
