Well, here's something I really like, unlike my previous two...
Shaymin Lite (OU Venusaur)
Venusaur @Life Orb
4Atk/252SpA/252Spe
Hasty Nature
~Leaf Storm
~Hidden Power Fire
~Earthquake
~Sleep Powder
Leaf Storm rapes things, HP Fire is generally great for coverage, Earthquake hit Heatran on the switch, outspeeding it as long as it lacks Scarf. Hence, something that can handle Heatran to test its set is recommended with this, like Tyranitar, Suicune and Swampert. Infernape is tricky, you can outpredict and EQ as he Swords Dances, or again you switch to a counter and nail it on the switch next time.
Here's some calcs on the power of Leaf Storm:
Gliscor: 89% - 105.1% (OHKO with SR)
Blissey: 26.6% - 31.5% (explained later, KO requires lots of Spikes and SR, and multiple Sleep Powder)
Dusknoir: 64.6% - 76.5% (2HKO)
Defensive Rotom-A: 77% - 90.8% (2HKO or OHKO with SR)
CroCune absorbing your Sleep Powder: 108.4% - 127.7% (OHKO)
The bulkiest Tyranitar you'll ever see (CurseTar?): 91.1% - 107.4% (OHKO with SR or OHKO)
Sleep Powder is what makes it a better Shaymin. Shaymin cannot put a pokemon to sleep reliably, instead relying on Leech Seed for Blissey. This means Venusaur could beat Blissey by forcing her out with Sleep Powder repeatedly with Spikes and finishing her off with EQ/Leaf Storm which does about 30% in my experience. But face it, is your opponent going to rely on Blissey 100%? I haven't been seeing a lot lately. Either way, it's still best to pack Tyranitar or something that kills her.
Who am I kidding, sleep move + 140 BP dent-anything-that-doesn't-resist-it-move = awesome spamming on the first turn out.
And yes, I have decided that AgiliNite is utter crap. It's still better to spam Draco Meteor with MixNite.