First of all: recruit Electrike. His/her lightning rod will protect you from Zapdos' electric attcks. If you are cyndaquil, use smokescreen and leave your partner do the dirty job, if not, get sleep seeds, allure seeds or blinker seeds.
you can find zapdos in mt thunder
its an expired event
he has about 1000hp
zapdos is in amp plains on 7F but you need a mystery part or a secret slab
What I did is keep on killing it until it asks to join. (If you want to recruit it make sure you hit it last when it faints, not your partner. You can tell your partner to get away while you defeat Zapdos.)
That would be Legendary Island. You get it when you recrit Articuno, Zapdos, or moltres.
u can find ZAPDOS in mt thunder by RESCUING SHRIFTY
30%
you beat mystery dungeon red rescue team after you prevent the meteorite and defeat RAYQUAZA!
you recruit him by going to electric plateau
He will be at Amp Plains, as long as you have the Secret Slab with you.
u have to defeat bulbasuar