Venusaur

Overgrow
Raises the power of Grass moves 50% when at 1/3 HP or less.
Type Tier
Grass / Poison BL
Statistics
Min- Min Max Max+
HP
80
- 301 364 -
Atk
82
180 200 263 289
Def
83
181 202 265 291
SpA
100
212 236 299 328
SpD
100
212 236 299 328
Spe
80
176 196 259 284
Name Item Nature

Disabler

Leftovers Careful
Moveset EVs
~ Sleep Powder
~ Leech Seed
~ Sludge Bomb
~ Synthesis
252 HP / 84 Def / 148 SpD / 24 Spe

Sludge Bomb is third here for a reason—Venusaur is not really an attacking Pokémon. You're probably going to be met straight up by a Skarmory, if not Celebi, so Sleep Powder should be your first move, then Leech Seed. Then fire away with Sludge Bomb, healing up when necessary. You should note, however, that Tyranitar's Sand Stream reduces Synthesis' recovery from 1/2 to 1/3.

This defensive Venusaur is good for walling Zapdos and Raikou, even those with Hidden Power Ice, for quite a while. If feel you already have enough special coverage and would like it to take Fighting hits, Swampert, or some other physical threat, focus on Defense instead (like demonstrated on the Special Attacker set). Venusaur's Special Defense is quite a bit better than its Defense, and he has more special resistances too, but it's not bad at it at all.

Name Item Nature

Physical Attacker

Leftovers Adamant
Moveset EVs
~ Curse / Swords Dance
~ Sludge Bomb
~ Earthquake
~ Sleep Powder / Hidden Power Ghost
208 HP / 192 Atk / 108 Spe

Not really a good idea with Skarmory running around everywhere, though with Magneton support this can work well. Earthquake is for the Metagross and Tyranitar of the Pokéworld, and if you're afraid of Ghost-types you should use Hidden Power Ghost.

The suggested EVs outspeed Adamant Tyranitar, even those with 252 Speed EVs, while having a healthy 353 HP to afford set-up time. If you're using Curse, remove all Speed EVs. Max out HP, and put your leftover EVs into Defense (if you want to be able to Curse effectively against other physical attackers like Snorlax) or Special Defense (if you want to take special hits well while tanking on the physical side).

Name Item Nature

Special Attacker

Leftovers Calm
Moveset EVs
~ Razor Leaf
~ Hidden Power Fire
~ Leech Seed
~ Sleep Powder
252 HP / 64 Def / 80 SpA / 56 SpD / 56 Spe

This is a special-based Venusaur, Hidden Power Fire is for Skarmory while Blissey can't do a damn thing to you when Leech Seeded and probably put to Sleep if it tries to stay in after healing or something. You'll probably be met with something like Salamence after a while, though, but that's what switching is for.

If Blissey is their only decent counter to Venusaur, then if you're careful, you can just hit it (and only it) with Sleep Powder. Say it's Venusaur vs. Blissey, and the other guy has Swampert and Skarmory waiting. If you put Skarmory to Sleep, then Blissey can come in and stall you out of PP with Softboiled, go for the Freeze with Ice Beam, or just be generally annoying with Thunder Wave Paralysis. When you put Blissey to Sleep, however, it might switch out to abuse Natural Cure, and then come right back in. Put it to Sleep again, as Natural Cure means you won't be violating Sleep Clause. You can do the same thing to potentially beat Celebi, but you have to predict Celebi switches, otherwise it can hurt you with a faster Psychic.

Other Options

Hidden Power Ice can beat Salamence on switches, but you need at least 270 Special Attack (136 EVs without nature) to even have a shot at OHKOing the standard Choice Band Salamence (4 HP EVs, no Special Defense EVs), 319 Special Attack is needed to guarantee the OHKO (216 EVs with a +Special Attack nature). If it's using the standard Dragon Dance spread (120 HP EVs, no Special Defense EVs), then 328 Special Attack (252 EVs, +nature) Venusaur has a 2/3 chance to OHKO Salamence.

Hidden Power Grass is a bit stronger than Razor Leaf and has 100% accuracy, but you have to sacrifice that high Critical Hit rate and a Hidden Power slot. Body Slam can paralyze Salamence, among others. Don't even think about Sunny Day + Solarbeam, Venusaur is too slow to use that kind of offensive set-up. Use Exeggutor or other Chlorophyll Pokémon for that.

Growth can be used to boost Venusaur's mediocre Special Attack, but if you want to sweep with a Special Attack, you should look into a good Calm Minder like Celebi. Light Screen can be used to help the whole team take special hits easier.

Roar can be used for pseudo-Hazing: it can Roar away a Zapdos with Substitute, Agility and / or Baton Pass decently, and is another alternative to stopping Calm Mind Raikou. It also defeats Ninjask (watch out for Hidden Power Flying). Charm can really annoy Salamence, Gyarados, Snorlax, and Swampert, among others. Protect scouts Explosion and Choice Band moves, and, more importantly, gives you more Leech Seed and Leftovers recovery. Toxic is a decent move for stall-oriented approaches, and can be paired nicely with Leech Seed. Just make sure you have a way to stop Skarmory and Celebi (Sludge Bomb can help keep Celebi at bay, and Hidden Power Fire can scare Skarmory away).

EVs

It's a good idea to run 12 Speed EVs or so to be faster than enemy Milotic at the minimum (more can be used for those Milotic that have a few Speed EVs of their own). Another important breakpoint is 208 or more, which requires at least 48 EVs, as this will make you faster than Suicune and Jolly Marowak. The next important point is 222 Speed, or 104 EVs, beating Adamant Tyranitar to the punch (most important with a Grass move or Earthquake, but Sleep Powder and Leech Seed are also nice to get in before the Taunt).

For the first set, Careful, give it 252 HP EVs for maximum tanking ability. After getting Venusaur to the desired Speed, split the rest in Defense and Special Defense, depending on what Pokémon you'd like to be more effective against.

Run Adamant for the second set, 252 Atk EVs, as much Speed as you want to outrun the Pokémon you want, and the rest in HP to cover your defenses.

The EVs for the third set are all over the place. It should be noted that you can't 2HKO Skarmory without Modest, unless you're willing to gamble on the random number generator. You need 306 Special Attack (176 Special Attack EVs, +nature) to guarantee a 2HKO on 252 HP, 0 Special Defense Skarmory, and 259 Special Attack (96 EVs, neutral nature) to even have a shot. You could drop Defense to raise Special Attack or Special Defense.

Opinion

Venusaur has great stats and a good support movepool. Its offensive choices, however, are somewhat limited. Statusing Pokémon is always nice, and Venusaur can put opponents to Sleep or Poison them (with either Sludge Bomb or Toxic), so if you think ahead and pack a Celebi / Blissey counter like Hidden Power Bug Dugtrio, you can effectively cripple any Pokémon you want and go from there.

Counters

Skarmory walls any set without Hidden Power Fire. Gyarados and Salamence come in easily on about everything Venusaur can throw except for odd Hidden Powers. Celebi sops up Leech Seed nicely, resists Grass, and laughs at anything offensive Venusaur throws at it, save Sludge Bomb. All of them run STAB super effective attacks to put a big hurt into Venusaur. Weezing, Forretress and Metagross aren't hurt by Grass attacks or Sludge Bomb at all, but you can put them to Sleep or Leech Seed them. Metagross is hurt by Earthquake and Hidden Power Fire. Gengar can hurt with Fire Punch or Ice Punch, he is immune to Earthquake and resists Sludge Bomb and Grass moves, so watch out for him as well.

Hypno and Banette don't take much damage from Venusaur's STAB attacks and are immune to Sleep Powder. The former can use STAB Psychic and the latter can Will-O-Wisp and Knock Off Venusaur's item. Heracross and Ursaring actually benefit from Venusaur's Sleep Powder, thanks to Guts Sleep Talk and a powerful STAB move.

Blissey hates Leech Seed and Sleep Powder but walls all Special Attacks and can easily survive two Sludge Bombs. Snorlax beats Venusaur in a Curse war, unless Venusaur is carrying Leech Seed. Regice and Articuno don't particularly care about Hidden Power Fire, and can fire off STAB Ice Beams, so staying in to use Sludge Bomb is risky.

Tentacruel makes Venusaur's life hard with Liquid Ooze and Substitute for Leech Seed, and it can either launch a super effective Ice Beam or a Swords Danced Sludge Bomb, although Earthquake can take it down.

Most of these counters need to be wary of switching into Venusaur, though, as Sleep Powder can put even the sturdiest foe out of commission if they are not prepared for it.