Take note, though, only the first pummel enters the stale move queue, so unless you just feel like racking up damage, only go for one pummel.
Wow, didnt know that
...
Well than I guess we gotta remember to try not to use bair until it's in kill range. This meaning don't waste your bair on dsmash at under at least 100%. go for a uair or grab (at real early %) instead. If your style is based on spamming bairs for pressure, then I guess you should try side b for kills during dsmash.
From what it seems, ZSS' only REAL reliable kill moves, or moves that kill the most often, are either bair, side b, or uair (when not decayed). based on your style, you have to try to save the move you need to kill with as often as you can so when it's need and used it will get the job done.