Seems like zigzag might have some shieldbreaker ability. While not actual shots, it seems like after it's been shot once, zigzag will "bounce" off shields and deplete them. If you get it at the right angle and time it right, this can easily eat a whole shied.
The "bounce" only does damage to shields though, not players so be ready to actually shoot if they drop/try to roll.
There's no real set-up for it though and the timing is super hard...
I've also been heavily testing with clay shot, specifically the shot timings.
On shield, there's three main timings I like.
1: No detonation to let it hover above shield. This is for when the gamestate is still relatively neutral and conditions them to think clay shot is more punishable than it is. This can let us run up and grab for huge rewards by throwing them into the frisbee and firing, though it's pretty easy for them to just roll away. I generally just throw out a gunmen.
2: Shot immediately to punish this conditioning
3: Shot slightly after to cover rolls, and the "i guess he's not gonna detonate" mindset.
On hit confirm, there's also three timings.
1: Immediate/Buffer, to make it most likely to connect. So it can catch chars with bad shield dashes, rolls/air dodges/spot dodges, and get laser priority so it beats more moves. Best at low percents where it still lets us combo.
2: Delay between frisbee hit and shots. This lets us combo off it at higher percents, by trapping the enemy in the animation longer so we can get close enough quick enough to follow-up.
3: SUPER delay. Only to be done at high/kill percents. The frisbee sends opponents very high, but with little hitstun. You do not detonate after the frisbee hit, but instead seek to punish their landing. If they air dodge, you can u/fsmash. If they just land, you can grab and down/up throw into the frisbee with properly timed shots. For some reason, when thrown into enemies like this, the shots just drag them down and not knock them back. This means we can get an upsmash while the frisbee drags them down.
This works best on mid/fast fallers at high percents, but on floaties it isn't so great. It won't generally work on them at kill percents, so it's not worth going for generally. You can try catching their jump away with upair/nair, but that's about it.
If done by the ledge, you can also bait out an air dodge after the frisbee hit for dair.