Okay, this is just sad.
So far, from my testings...
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Zero Suit Samus:
F-Tilt
F-Smash
Dash Attack
Jab
Paralyzer (Neutral B)
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This essentially eliminates half of her ground game, one of her greatest kill move, and her best combo starter.
Her main kill moves, as far as I can tell, is her recovery move and her F-Smash. Kirby can easily air-dodge her recovery move and punish her, and duck under her F-Smash.
Might be more, but those findings are from a couple of FG ZSS matches. Ducking under her grab may be possible, but I'm not sure.
EDIT:
More testing is needed, but Kirby can duck under ZSS's main spacing tool, Plasma Whip (her Side-B). I'm not sure if he can duck under the end of it, but I was able to duck under it while I was next to her several times.
EDIT2:
Just ducked under her grab. Needs more testing, similar to her Side Special.
EDIT3:
Okay, ducking under grabs is confirmed - doesn't matter on spacing, Kirby can duck under her grab. Sadly, I'm not sure about her Dash Grab, but I'm sure it's the same thing. Her Side Special is a bit confusing - I was able to duck under it sometimes, but couldn't at other times. This requires more testing.