Bair can be used. You can stagepike people with it, or just boink them away from the stage. Fair spike if you are a showy mfer, but you really shouldn't be going for edgeguards all that much. Fox is, alas, pretty bad at fighting offstage in this one. It usually isn't worth it, (unless you are up against Mac) as it puts you at risk (Fox drops like a rock) and thus lets your opponent possibly turn the game around. It's best to wait onstage and punish them as they come back.
With customs on, you have a good few more options. You can use B3 to make them recover high (it sends them so far that it will gimp many characters unless they go over it, so they will), B2 to hit people just as they jump and rob them of that option, or downB2 to just push them away from the stage (the windbox is very strong, but your horizontal recovery is so good that you can often make it back to stage without jumping, so big shine->jump after them->big shine is viable).