In response to the Fox vs. Zero match-ups, I'd like to provide some input.
As a dedicated Fox main in Brawl+/vBrawl, I can see where Fox would have the advantage in some respects. I really think that there are a few factors that have not been considered though. (I will respond in regards to B+ only.)
A.) Zero has his shield. Thus, Fox cannot force an approach. SHDL (Short-Hop Double Laser) Is integral to Fox's damage wracking game, and an attentive Zero player will not have to deal with this to the extent many other characters do. If Fox tries to rush once you pull out the shield, throw it and dash away, Power-Shield, or interrupt his rush with Jab combo or FTilt.
B.) Zero does have many options to keep Fox from getting the combos going, and the CC-Dash provides superior spacing tools for him to use. Is Fox trying to rush you down? CC-Dash to FTilt/pivoted FTilt is your friend. (Especially with the forced tech-chase caused by tripping.) Is Fox approaching with short-hopped Nair/Dair? Zero's own SH-Fair, SH-Bair and SH-Nair are disjointed and fast enough to get him off of you. Bair is a good tool because no-one expects it to hit both directions, it comes out fast, and you can short hop it out of Side-B to catch the opponent as they fly/run into you. Is he trying to Dash-Shine you? Dash-Jump Nair is the answer. Also, Zero's basic Dash-Attack from Side-B and Jab combo from CC-Dash give him even more zoning and damage-wracking tools on the ground.
C.) Fox is decidedly more deadly on-stage, namely because once the combo starts, you'll be taking a good amount of damage before it's over. However, Zero's off-stage options far outweigh those of Fox. Leaping out to gimp with a Dash-Jumped Nair will eat through Firefox or the Illusion. If your trying to gimp from on-stage, wait until he's about to sweet spot and send him plummeting with FTilt. (Works on Firefox AND the Illusion, the latter requires better timing.) If he tries to recover above the stage, Uair works wonders, both for it's decent KB and the angle. Fox is a fast-faller just like Zero, and pays for it considerably when a character like Zero has him off-stage
D.) At lower percents, Fox is grab fodder for Zero. Well spaced Zair>Grab can be a nightmare for Fox to penetrate reliably. The Zair>Grab also gives Zero a good zoning tool to use even if his shield is out. Once grabbed, Most throws can be followed up well with Dash-Jump (Short-hop) Nair or Dair. Beware though, Zero is just as vulnerable to grabs as Fox is. If you get grabbed, prepare to eat a buffet of Utilt, Usmash and Uair.
Really, the biggest problem I can see in this match up is if Zero gets punished for poor spacing, or if the Zero player tries to use on-stage killing methods only. Fox's biggest assets against Zero are definitely SHFF Nair and Dair>Utilt. If Fox connects with Utilt at low to mid percents, he has a plethora of combo/string options available to him.However, Zero can shut down most if not all of Fox's approaching options if used correctly, and if a combo starts, Zero can usually escape without too much damage with proper DI and Nair/Nair-Down.
That's all I can really think of at the moment, If anyone else can think of other issues, I'll test them out.
~X