Arbok:
If opponent's poisoned, he can do 50(which he maxes out at) (80 to gallade or gardevoir)
-if poisoned, then at least 10 in between turns
That's 90 damage so far possible.
You either need 2 weezings to get 110 damage, or FOUR weezings to KO gallade.
Sure, they can die after their turn, but if they get the oppurtunity to retreat/hit you then it's not as good of a deck.
That leads me to believe that arbok alone is not good enough.
Crobat:
It has free retreat, a resistance to gallade, and has 20 more hp, but it's an extra stage.
It's power is pretty nice. That means that if you use it's power vs GG/magmortar:
You do 50(+30 to GG), and up to 80 to GG. The power adds 20, so it's at 70 to mag and 100 to GG.
Now, with a weezing, it's 110 to GG (a magic number) but still very far from magmortar.
Ideally, you will force magmortar and GG to use their rare candies for fear of a 50 damage snipe early game killing a skitty, ralts, cyndaquil, etc.
Toxicroak:
Very low damage maximum, but 10 more HP than arbok, bringing him to 90 which is an odd number. As I've noted in the past, reaching an odd-numbered HP is crucial in this game. 90 is nice for a stage 1. His attack also consistently does at least ~40 damage. You will get the most consistent weezing use with a toxicroak, as the opponent MUST retreat to remove poison, and because you poison any time you attack with toxicroak.
Beware of a few things:
1. Unown G- stops arbok and toxicroak. Holon WP/GL also does a lot of hurt to this deck.
2. Sydney's Stadium- People are thinking about Sydney's stadium with all the status increasing this set has introduced
3. Xatu- People who work with Wailord or Wigglytuff or Primeape might use a Xatu- which REALLY hurts this deck. The opponent gets the same advantage as you do, but without them taking up the cards in the deck for it, or the resources to bring the pokemon into play
This deck doesn't seem to have a reliable answer to Magmortar or GG. Heck, even new decks like wailord or Weavile variants will probably get by this.