fox is falcos hardest matchup
hes faster and ***** just like falco
you have to play very careful, usually trying to rush a fox down youll be hit/grabbed everytime.
try to keep your distance, lasering etc
get in quick bthrow kills.
and yes fox can cc a dair from falco if you jump dair instantly, if you jump ff then aerial then fastfall he shouldnt be able to, also you cannot cc a fox's dair its multiple hits stunning you
at low %'s you can cc his nair if he doesnt shffl properly but if he does the fox should be 100% safe, so the only thing you can really do when a fox is aerial you is roll or learn to jc shine out of shield or just jump shine instantly as he hits your shield with the areial.
you can also always wait for the shine. almost all foxs will aerial then shine leaving them safe, once the fox jumps out of his shine or wavedash's follow up with an attack.
uptilts are always your friend, test out uptilting to stop his approaching aerials
it should help out.
alot of foxs also like to waste their double jump to create mindgames
they will jump in make it look like they will hit then waste their jump so u grab etcetc then come down, if this is your case then wait for him to double jump then hit him with a aerial etc.
trying to do long drawn out combos are pointless vs fox
pay attention to what your doing, make your combos count, dont try to be fancy watch which way he di's, which way he rolls.
tech follow dairs are dangerous so use them.
at certain %'s you can dair fsmash sometimes they dont expect it so they miss Di causing a low kill.
stay away from fox when hes next to the edge fox's 0% shine kills are gay lols
most of the time vs fox youll be close together since foxs like to pressure people into doing stupid things, in that case up wait for him to attack uptilt, dash dance out of the way dash attack or dair whatever feels right at the time.
try to get cheap kills, bthrow fsmash is a very easy way to do it.
hope that helps a lil bit. =]