I'll try to keep this brief. It's rather difficult to judge this slate, mostly because the different weather styles are vastly disparate in viability.
Drought Virizion: I like this quite a bit. Synthesis becomes a great method of recovery, but is still somewhat limited because of its low PP. Solarbeam is great, and Viri doesn't need Giga Drain anymore due to the extra recovery from boosted Synthesis. HOWEVER, sun is something of a double edged sword for Grass-types due to the increase in fire attacks' power. That being said, Viri gets Close Combat for Heatran, although a Drought Viri user would run the risk of empowering Talonflame. Stone Edge mitigates this somewhat. It's good, but I'm not sure it's the best.
Snow Warning Glaceon: I really wish GF would buff hail; a Def boost to Ice-types (mirroring the S.Def boost to Rock-types in sandstorm) would be a consummation most devoutly to be wished, but that's irrelevant. As it is, Hail is not good, and Glaceon is SR weak, meaning that you lose 1/4 health switching in to set hail. Perfect accuracy Blizzard is good, but you'd need Specs to maximize its effect, and I prefer weather setters to be more support-oriented. Blame GF.
Sand Stream Cradily: What's Cradily, yo? I like this one too; Cradily has great synergy with Excadrill as it doesn't stack a weakness to Water, and isn't as weak to Fighting as T-Tar. The Grass STAB is great for sucking massive amounts of health from Azu andM-Luvdisc Alomomola, although Keldeo could still ruin its fun with Secret Sword. The main problem I have with Cradily is its major lack of offensive presence as compared to T-Tar or Hippo. Still very good, though.
Drizzle Blastoise: This is my favorite, mostly because it offers massive offensive presence via its M-Evo late-game. Its bulk is good compared to Politoed, but it probably wouldn't want to hold a Damp Rock, so it would need a secondary rain-setter, which isn't too hard to find (Thundy, Torn[-T], &c).
Drought Virizion: I like this quite a bit. Synthesis becomes a great method of recovery, but is still somewhat limited because of its low PP. Solarbeam is great, and Viri doesn't need Giga Drain anymore due to the extra recovery from boosted Synthesis. HOWEVER, sun is something of a double edged sword for Grass-types due to the increase in fire attacks' power. That being said, Viri gets Close Combat for Heatran, although a Drought Viri user would run the risk of empowering Talonflame. Stone Edge mitigates this somewhat. It's good, but I'm not sure it's the best.
Snow Warning Glaceon: I really wish GF would buff hail; a Def boost to Ice-types (mirroring the S.Def boost to Rock-types in sandstorm) would be a consummation most devoutly to be wished, but that's irrelevant. As it is, Hail is not good, and Glaceon is SR weak, meaning that you lose 1/4 health switching in to set hail. Perfect accuracy Blizzard is good, but you'd need Specs to maximize its effect, and I prefer weather setters to be more support-oriented. Blame GF.
Sand Stream Cradily: What's Cradily, yo? I like this one too; Cradily has great synergy with Excadrill as it doesn't stack a weakness to Water, and isn't as weak to Fighting as T-Tar. The Grass STAB is great for sucking massive amounts of health from Azu and
Drizzle Blastoise: This is my favorite, mostly because it offers massive offensive presence via its M-Evo late-game. Its bulk is good compared to Politoed, but it probably wouldn't want to hold a Damp Rock, so it would need a secondary rain-setter, which isn't too hard to find (Thundy, Torn[-T], &c).