It's time for some Poison Rankings!
First up, Scolipede, for A Rank!
Ability: Speed Boost
Moveset: Poison Tail, Megahorn, Pursuit/Rock Climb/Double Edge/Baton Pass, Toxic/Venom Drench/Sunny Day/Protect/Baton Pass/Toxic Spikes/Spikes
Analysis: Scolipede has a fantastic Attack, but an even better Speed, especially with its ability Speed Boost. To make use of its Attack, Poison Tail and Megahorn are its best STABs, and you can also put Pursuit, Rock Climb, and/or Double Edge on its moveset. However, because Scolipede has Speed Boost, you probably want to have Baton Pass on it, to pass some extra Speed to another Poison Pokemon. You also could use Protect to keep it safe for a turn so it gets at least one Speed Boost off. In addition, there's Toxic for wearing Pokemon down, Venom Drench for tough Pokemon that rely on their abilities to help them out, Spikes or Toxic Spikes (Toxic Spikes especially if you are using Venoshock on some of your Pokemon), or Sunny Day if you have Chlorophyll Venusaur or Vileplume on your team, since Scolipede can almost always get a Sunny Day up. Scolipede's capability of dealing damage and also supporting team members makes it a valuable member in a Poison Monotype.
And now, Weezing, for A/B Rank!
Ability: Levitate
Moveset: Sludge Bomb, Explosion/Destiny Bond, Pain Split, Poison Gas/Haze/Toxic Spikes
Item: Black Sludge
Analysis: Weezing is another defensive Poison type Pokemon, so it's probably going to be outclassed by something, whether it be Amoonguss or Muk or whatever, but it does have a very useful niche: Levitate. Weezing, Crobat, and Gengar (who is not available in E15 anymore) are the only Poison types with an immunity to Ground type moves (especially Earthquake), and Weezing is probably your best bet if you wanted a bulky Pokemon of those three. It also can learn Sludge Bomb, which has a 30% chance of Poison, which is pretty useful for wearing Pokemon down, but if you want something guaranteed, Poison Gas and Toxic Spikes are also possibilities. Haze can be useful if your opponent tries to set up, such as Florinia's Cradily. There's also Pain Split and your Black Sludge for some recovery, but if you know you're about to faint, use Explosion or Destiny Bond! Overall, Weezing is a very useful bulky Poison type with its Levitate, even if there are better Poison types. If only we had TM Will-o-Wisp...