If you are just trying to weaken the opponent enough to set up DDtar, then you could use a lax without Rest. Eq, shadowball, fireblast, return/bodyslam/double edge, curse.....all are good options.
The reflect/wish jirachi is really good. There are many options I would have you consider to use reflect/wish jirachi again.
You could use psychic/thunder, psychic/cm, thunder(bolt)/ice punch, psychic/fire punch.
Flygon would be good as a CB Flygon. You have 3 pokemon with a fire type move. It is more essential in D/P to use fire type moves, but in R/S/E, fire is not needed as much. Dont spread the EVs as much.
I might actually go with a simple EV spread for Zapdos. Something like this:
Zapdos @ Leftovers
EVs: 252 HP / 128 Def / 128 SDef
Bold Nature (+Def, -Atk)
- Hidden Power [Grass]
- Sleep Talk
Snorlax is already a good special sponge.
I can understand the WoW in the cause of setting up DDtar, but you may consider Giga drain on gengar for swampert.
Sub on tar protects it, but using HP bug will give you better typing coverage. Its your choice. You may consider a DDtar with Lum Berry as long as you have reflect, wish, and WoW.
Heracross can do some damage to your team if you are not prepared.