Hmm. Alright, let's think about this.
We can discard Floe and Sora; their types don't match.
That leaves us with Nero, Opal, and Muscat...
Nero knows Tackle, Leer, Charge, and Spark. He's electric and is neutral against Zapdos.
Tackle probably won't work, leaving Spark as our only attacking option.
Opal knows Growth, Mega Drain, Stun Spore, and Magical Leaf. She's grass/poison and is also neutral against Zapdos.
Stun Spore's effectiveness is... questionable against a flying electric bird. That leaves Mega Drain and Magical Leaf for attacking.
Muscat knows Bite, Water Gun, Rollout, and Leer. He's rock/water and is effective against Zapdos's flying but is weak to its electric.
Bite won't work unless Muscat is secretly an Olympic high jumper. Water Gun is not effective. Rollout involves rolling and probably won't be effective. Leer doesn't attack.
So Muscat's probably not the way to go.
So our choices are between Nero and Opal?