Because Dazzling Dance and Unstable Shield share the same ability slot (#3), and both times you'll be using this on the first round, we can combine their moves in one line by saying ability(#3), and indicating it needs to happen on each pet's first rounds with [self.round=1]
You have to put the self. before the round. If we just do [round=1], that's the first round of the entire battle and it won't work for the Woodworm, because he technically comes in on round 3. We also don't want Dazzling Dance to apply again, so we need to indicate either a round or an aura. But, since we know we want Unstable Shield in a self.round as well, it just makes sense to combine them.
Since we indicated that Dazzling Dance would only happen on round 1, we can just put Howl beneath that line with no conditionals.
At this point your Fox dies, and the script goes through the lines until it hits:
We can use this, and we don't have to specify what pet to change to, like change(#2) [self(#1).dead]. That's a little wordy, and not necessary. change(next) works just as well because your pet is dead, and none of the lines above change(next) will run from the script.
The script brings in your Woodworm, and again, uses:
Because, as mentioned before, this will apply Unstable Shield.
Then, with no other abilities listed, the script hits:
We don't need to put any conditionals on standby, since that's all you need for your pet to pass with the script. We put this right above change(next) so the script won't miss any abilities that need to happen.
Hopefully that was helpful. Let me know if you have any questions! (edited)
Also, I'm not sure why this works with the Woodworm's shield, but not other shields from pets with similar power stats. I have a B/B Woodworm, who has the same power stats as the Thundertail Flapper, but the Thundertail couldn't kill him with one round of Alert!, while the Woodworm could. There's nothing in the tooltip to indicate why Unstable Shield is better than Lightning or Fire Shield.
That said, the H/H Woodworm might need an extra attack because its power is at 260, but until someone with the H/H tests that, I wouldn't be able to say one way or the other.
Testing some of the other shield pets, for those looking for alternatives, here's what I've found works:
Anything with a power of 300+ should be good to Shield > Pass
Anything lower will requite extra attacks. Or, in Tinytron's case, double shield then Flamethrower.
I'd avoid the Son of Skum altogether. The Thunder Lizard Runt will be risky, because of Beasts taking extra damage from Mechs, and you'll need to Akunda's Wrath to finish Goldenbot off.