Team needs compeltion - Help Please

[homsar]

Ok, so heres what I got so far:

Team at a glance: Jolteon/Arcanine/Snorlax/Porygon-Z/empty/empty

Jolteon
@Leftovers
Careful
252 Spe / 252 SpA / 4 HP
Shadow Ball
Thunder wave
Thunder Bolt
Toxic

Im using Jolt as my starter. Thunderwave to try and force a switch then toxic the next one. And I know that nature isn't the best. I may or may not get a new one.

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Snorlax
@Leftovers
Brave
252 HP / 252 SpD / 4 SpA (could be wrong, did a long time ago)
Focus Punch
Substitute
Return
Crunch

Hes my special wall. Though he is a bit unconventional he has served me well and has taken down the likes of ubers. Not much else to say here.

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Arcanine
@Charcoal
Adamant
252 Atk / 252 Spe / 4 HP
Flare Blitz
Extreme Speed
Thunder Fang
Overheat

The standard physical set on him. I know I need to give him choice band or scarf, I just haven't gotten around to getting them yet.

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Porygon-Z
@Choice Specs
Modest
4 HP / 252 SpA / 252 Spe (I can only assume as I got in a trade)
Tri Attack
Thunder Bolt
Ice Beam
Dark Pulse

The basic sweeper here.

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The next two slots I have no idea. Obviously I need a Defensive wall but other then that I'm clueless. For one of the slots I was considering Jirachi with the following:

@Chesto Berry
Bold
(dont know yet)
Doom Desire
Psychic
Swift/Protect
Rest

or

@Leftovers
Bold
252 HP / 224 Def / 32 Spe
Doom Desire
Wish
Protect
Psychic
(AKA the one off smogon)

So what do you think of the first four and what should I do for the last two slots? Is jirachi a good idea? Help much appreciated.