..so essentially you want help finishing your team.

Well if you've got a Metagross trained already and you want to use Specsmence, try this:

Umbreon @ Lum Berry/Leftovers
252 HP and Defense, 4 Special Defense
Relaxed or Sassy
- Mean Look
- Baton Pass
- Wish
- Toxic/Taunt/Protect


Trap Blissey or Cresselia with Mean Look, Baton Pass this Mean Look to Metagross, and Explode on their special wall.  That should make sweeping with Salamence a lot easier.  Alternatively, you can also use Wish, and then Baton Pass the next turn to send the healing to another Pokemon on your team (the reason you want to use a - speed nature is so that you will be guaranteed to go last on the turn the Wish will activate, so that Umbreon can take damage and then you can bring out the Pokemon you want to heal, instead of risking KOing the Pokemon you want to heal by switching it in at the beginning of the turn).  Toxic isn't going to be used often, but it can be of situational help.  Taunt, on the other hand, could be useful if you want to try to trap a second wallish Pokemon that carries Roar or Whilrwind (examples: Skarmory, Swampert) so that they won't Roar you out while you are setting up your trap-kill.  Finally, Protect would allow you to heal Umbreon with Wish without taking any extra daamge the second turn, and could in general be a good turn-waster.  It's all preference really.

Another Pokemon with Explosion would be a nice addition to this team (Gengar with Life Orb would work nicely, as it could take out something).

Finally, since all of these Pokemon I have mentioned could be easily KO'd by Choice Scarf Heracross, something like Gliscor in your last team slot to counter it wouldn't hurt at all.

If you need better IV's on a Salamence, I've got some NICE Bagons about to hatch. They're the offspring of my shiny Charizard (y'all know how good his IV's are!) and a Shelgon that either had perfect speed or perfect sp.atk (can't remember) and hopefully the babies know Fire Fang too, even though that's not a move you're looking for. (I'm breeding these Bagons to know that move in case anyone ever wants it. Then I'm going to continue leveling Charizard and getting new moves for him.)

So as of right now, I see an emphasis on Special Attack, and both Salamence and Porygon-Z are great for that, but you really need a Bulky Pokemon to take some hits. When I still had my copy of Pokémon, people didn't think much of him, but I used a Slowbro instead of the typical Swampert. He blends water and Psychic together well, and if trained properly, he can take quite a few hits, and be the bulky annoyer you want to balance out your team.
Here's what my Slowbro looked like:

Slowbro @ Leftovers
252 Def/212 HP/ 44 Sp. Atk
Bold
     Own Tempo
-Surf
-Grass Knot/Ice Beam
-Thunder Wave
-Slack Off

I personally had two Slowbro, and used them accordingly depending on what the situation was, but I had one with Ice Beam, and the other with Psychic. Because your team incorporates Special Attack though, it isn't all that necessary. Anyway, the strategy here is to resist off most Sweepers in the game, such as Garchomp. Slack Off is probably his most necessary move. Even if you don't follow my moveset, keep Slack Off. Thunder Wave works out because Paralysis can be such a pain, and there is a small chance that the Pokemon won't be able to fight at all. I personally would use Ice Beam, just because it can take out a lot of Slowbro's weaknesses, for decent of super effective damage. Surf's just necessary honestly. No good Bulky water is without it.