Erm, how are the birds exactly beating Zapdos, unless the Zapdos player were to run literally no other attackers? (Everyone knows pure Zapdos is crap). Zeraora and Pikarom one-shot it, Jolteon GX one-shots it after one Choice Band + E-power or 2 E-powers. The only electric attacker that doesn't do jack to it is Zapdos, and Zapdos does jack to any GX mon anyway. Stall also tries to run as little meta relevant weaknesses as possible, so there it goes its chance in stall unlike Magilord whose weakness is not as meta prominent. Electric weakness in this meta is terrible, even with that huge HP.
Yes, it has a bad weakness, but Pikarom has a bad weakness and it doesn't care.
The birds WILL take 3 prizes with their GX attack against Zapdos. If your opponent limits themselves to 1 Jirachi and 1 Zapdos, they'll lose by not having the cards they need.
Pikarom can get 1 shot with the primary attack (with choice band).
That's 6 prizes.
If they bench a Pikarom they basically lose.
Jolteon/Zeraora would be the play against this but still, the birds have to get ahead by
1 prize to win.
It would be a close game.
Yes, I admit setting up a stage 2 against Zapdos is sketchy.
Yes, Pikarom will dominate some games.
But the birds will put up a good fight.
(You can kind of play around the dos by using victini and then koko prism to power up turn 2, going second. You don't really need porygon until your first birds go down.)