I might be an unorthodox Fox. I'll listen if you disagree with any of my philosophies. Here's my take on Fox in teams:
1. You really shouldn't feel the need to approach, mainly because Fox isn't good at approaching. Fox is not a character you use to overpower someone. I'm not really saying you should camp... you just need to be opportunistic.
2. You need to be good at changing targets (between your two opponents), and you need to be aware of what both of your opponents are doing and what their percents are. I think your main purpose in teams as a Fox player is to get up smash kills. If you see that opposing Metaknight at 90%, stop trading hits with that Wario at 30% and go up smash the Metaknight... it takes a fraction of a second, and if the up smash connects, Metaknight's dead. Also, if you realize your opponent is in killing range of your up smash before he himself realizes it, then that's perfect for you.
3. I should probably build up cred on the Fox boards before throwing out an analogy like this, but here it goes.
If it helps to think of it this way, you can think of Fox as a rogue class in an RPG. You don't want to be noticed by your opponents, and you kinda don't want to be in close combat with them, but you do want to backstab (up smash) your opponents when they aren't aware of you.
4. That's about it. My suggestions aren't things like... mix shine->nair into your approach to throw off your opponent. They're just broad 2v2 concepts.
p.s.
running upsmash says hi. That is all.
^^ crappy advice is crap
Toronto Joe, this reply makes me sad.