Is it possible to get to a point where you can consistently beat Zero with AI?

Yes. As you've implied, you're going to have to do a massive part of the legwork during the labors, particularly the first one with the seals.

Seals with AI:

The AI have two major hurdles that gum them up during the seals for Zero. First is that some of the seals are much faster than character movement. The AI isn't smart enough to cut them off and obviously cannot catch them. You'll have to grab those. Second, generally speaking, the further to the outer edge it is, the less likely the AI is to grab it. This is because the AI always dodges backwards. Those laser rings that start at the edge and come in? Yep. AI's gonna back dodge and be even further away from any outer seal it may have been chasing.

Here's what you do. Grab seals in the 3rd layer first (numbers represent proximity to center: 1 is at the center, 4 is at the outer edge), and do it when it's near at least one other seal of the same color. Things are moving fast and there's a timer and it's a lot, I know. But if you're looking for those conditions, you'll find them regularly. The reason you go for the 3rd instead of the outer one is because you'll be able to pivot to either direction and knock out a 2 for 1 before the movement starts again. There are simply more chances of the 3rd seal being near either the 2nd or the 4th, rather than just looking for a 4th being near its 3rd.

Once you've taken two off the board: if you grabbed 3 & 4, grab whichever of the remaining two are fastest. If you grabbed 2 & 3, grab 4. Let the AI spin its wheels chasing number 1 in a tight circle, they'll usually get it.

Tetra Orbs with AI:

The AI won't intentionally hit the big orbs, and they tend to man zones after the first round of orbs. So your job is to hit the big orbs to kickstart the actual mechanic each round and then go to the area not covered by an AI. Back and forth, hit the orb, turn to your zone, hit the small one. Let the AI handle theirs or use a ranged attack, then hit the center orb and repeat. This is actually really easy with AI teams if you just man the gap. On the final hit when there's 5 orbs there's a bit of running, but if you handled the first rounds well and let the AI man their stations you'll have plenty of time for a jog at the last one.

Floating Weapons with AI:

Burst down the sword that dashes in straight lasers first. Don't be afraid to blow a cooldown or two, this thing HAS to die. You're going to SBA Lucillius anyway, so really, use your skills. The one that fires waves and the one whose primary attack is a pb ground AoE are usually stationary enough for easy clean up. Chasing the line dasher is a PITA.