To start with I didn't know Zamus' Down B spiked. The first time it happened I just kinda stared at the screen stunned.
Try get her below the stage. Be in mind that Sonic's dair outprioritizes both her upsmash and Up B, so that's pretty good for gimping. Approaching from the air is also easier because of this.
Zamus is like one of the only characters who can gimp Sonic, which is a pain. She can do it to all characters, but be wary when recovering from a below via a spring that a Zamus can Stun Gun you to a Down B spike. Basically, don't recover too close to the stage, and more importantly use variety in your recovery techniques.
Cancel approaches a lot. This is obvious because Zamus outranges Sonic. She will knock you out of grounded approaches if you are predictable and not mix it up.
I tend to stray away from spin approaches in this match-up and bait out laggy moves like grab and Paralyzer Whip which Sonic has the speed to punish with like a dash attack or a grab, though probably the latter because I'm a grab
whore.
Once you're up close, Sonic does pretty well. IIRC, her Side B (Paralyzer Whip) will not hit you if you're close to her, so rushing her for an approach doesn't seem like a bad idea.
Sonic has the speed to mess with ZSS's parts (lol) but good players throw them upwards and so make it kinda risky to move in.
It's old, it's outdated, but meh.
http://smashboards.com/showthread.php?t=171377
Ignore the MASSIVE bias on ZSS' mains part to start with haha. And prepare for the massive walls of text on the second page from ShadowLink84 and Tenki. I'm about to pick through the thread now to find stuff that may be useful.
Anyway, I have quite a bit of experience on this match-up and have to say I see it as dead even, 50:50. (or maybe like 51.24:48.76 or something lol)
It's just that Zamus needs to space well against Sonic to stop him walking all over her, and with Sonic's speed it often proves difficult for her.
1000th post? I think so.
Edit, a few points, credited to Tenki.
Alright, so after playing against Snakeee a bunch more in the past month or so (wifi, sorry guys), I'll settle on this being an even matchup.
There are certain things to be taken into account aside from the usual Sonic disadvantages (priority,range,weight,projectile), so I'll try to address them.
The game is very momentum-based.
The beginning is crucial - if Sonic knows how to use them well and manages to take control of them, the armor pieces become a liability to ZSS. Sonic has one of, if not, the longest glide throw slides in the game, meaning he can do approaching slides while neutralizing your paralyzer, set up edgeguards to supplement his gimp game, retreat while attacking, as well as gaining a projectile to extend his reach. His speed can make taking control of items an issue.
PARALYZER...works. For the most part.
However, it is completely destroyed by Sonic's F-air. But don't feel bad, his F-air outprioritizes MK's side-B. Homing attack also tends to punish immobile shooters, so don't be TOO reliant on it.
Missed grabs are bad, but everyone knows that already. However, if he does a move with commitment to it (smashes, dash attack, initial charge to spindashes), you can grab him out of that, and accurate grabs are super effective.
Spotdodges are good, but aren't too abusable against a Sonic player, since many of his moves can cancel and have multiple ways of breaking out and punishing, or baiting moves and punishing your attacks.
If anything, some Sonic players prefer to D-air out of spring. If it's a grounded spring, you can camp the landing (it's about roll distance from the spring) with your punishment move of choice.
Other than that, I think the whole 'whoever gets under who' is pretty much right for ZSS. I play a pretty sh/ground-based game and less on juggling, but ZSS definitely feels like she has the advantage in an anti-aerial game.