I don't think Brinstar is a good CP to take Zamus to. The small blast zones make it easier to kill us. Brinstar also seriously limits our Arrow game due to the destructible parts of the stage, unless you take the time to destroy them, but that's a waste of your time.
As for Halberd, it kind of depends. I think any attempts at sharking can be seriously punished by ZSS's Dsmash. The low ceiling also makes it easier for her to get a ceiling kill, which isn't good because her best aerial attack is her Uair. I think taking ZSS to Halberd wouldn't really effect the MU too much. During the flying phase, we can camp her but she cancels out our Sharking attempts. When the stage lands, it's basically a contest to see who can get the other off-stage first, and who can use the stages gimmicks the best. Although, I don't think it'd be wise to CP to Halberd just because of good Uair+Low Ceiling =/.
I think the MU is 50:50 to 55:45 Pit.
Even though being above ZSS can be dangerous, I think we have more tools to deal with that than ZSS does when she is above us. We have more jumps and can sort of stall by using WOI if we need to fake out a landing. I think it just depends on which player is more skilled, since both characters are pretty equal when they go head to head, with a few advantages in some areas. I'm pretty sure Pit can wrack up damage faster than ZSS can, though. The fact that we have a reflector also helps with the Armour pieces and the occasional Neutral B. Pit just has to watch out for ZSS's speedy attacks and deadly set ups.