zapdos EV spread:
(Zapdos) @ Sitrus Berry
Trait: Pressure
EVs: 8 HP / 112 Def / 148 SAtk / 108 SDef / 132 Spd
Calm Nature (+SDef, -Atk)
- Thunderbolt
- Heat Wave
- Detect
- Tailwind
this is going to help you a lot, because it will be able to live a lot more moves, but you will still be able to do a lot of damage. it tanks latios's draco meteor all the time if it is timid, and some of the time if it is modest. this is with the dragon gem boost. it outspends neutral natured 252 speed base 80 pokemon, such as mamoswim and chandelure. it also tanks any rock slide in the metagame. this is the biggest change i think you needed to make, because if you want it to give you tailwind support it will need to live moves. and your current EV spread won't help you live too many attacks really.
that is the first change that i think will help you a lot.