for kirby: if he whores the forward smash a lot, it's really easy to shorthop over it and then hit him as he recovers with some down air + utilt + uair or nair or w/e you wanna do. I have a friend who is decent at smash and plays kirby a lot, and at least a few times every game i can trick him into forward smashing so that I can punish him as he recovers. Try not to clash fairs or bairs with him, as kirby's drill will almost always get priority. Also, don't be afraid to hit him from underneath - ness's uair has great priority.
When I fight a fox, i generally play defensively and attempt to utilt him if he comes in with a dair combo or try to get him with some shorthopped airs. Also, once he's off the edge, his comeback is incredibly easy to spike, so spike him like mad! Oh yeah, and kirby's up+b is very spikeable as well if it's coming from below.
Well hope this somehow helps.. i'm sure it's just silly and confusing, though.