Base Stats:
Hp- 80
Atk- 82
Def- 83
SpA- 100
SpD- 100
Spe- 80

Overview:

Despite being outclassed by it's Mega, Venusaur still has a niche in competitive. Venusaur is an excellent choice for sun teams, as it packs a good Speed tier, offensive stats, and most importantly, bulk. It also has useful moves such as Growth and Sleep Powder to break teams. Venusaur is exclusively a choice for sun teams, as it is outclassed by Roserade and Shaymin otherwise. Moreover, Venusaur gets completely walled by offensive Dragon-types such as Dragalge and Goodra. These threats get a free switch into Venusaur and can threaten its team. Despite its doubled Speed in sun, Venusaur is still outsped by threats such as Choice Scarf Trace Gardevoir. On the other hand, Venusaur lacks the necessary power to break teams if it tries to outspeed these threats with a Timid nature.

Moveset:

Sun Sweeper: NUbl
Venusaur (@ Life Orb / Grassium Z)
Ability: Chlorophyll
EVs: 4 Def / 252 SpA / 252 Spe
Nature: Modest (+SpA / -Atk)
- Growth
- Sludge Bomb
- Giga Drain
- Hidden Power Fire

Moves:

Growth increases Venusaur's Attack and Special Attack by two stages in sun, making it a threatening sweeper. Sludge Bomb is the strongest attack, hitting Fairy- and Grass-types such as Florges, Shaymin, Virizion, and Comfey for super effective damage. Giga Drain takes care of bulky Water-types such as Milotic and Blastoise, as well as replenishes lost HP from Life Orb recoil and damage. Solar Beam can be used over Giga Drain for more damage output at the cost of only being able to use it in sun. Hidden Power Fire is used to hit Chesnaught and Escavalier while chipping away HP from the likes of Bronzong and Doublade. It is also stronger in sun. Sleep Powder is an alternative to Growth, allowing Venusaur to induce sleep on a threat to allow a teammate like Leafeon to set up Swords Dance much more easily. It can also be used over Sludge Bomb to make Venusaur more threatening in the sun due to Sleep Powder + Growth, but then Venusar will heavily rely on sun to do any significant damage.

Set Details:

Maximum Special Attack and Speed EVs with a Modest nature are used to ensure Venusaur gets the best out of its wallbreaking capabilities. A Timid nature is optional to Speed tie with Choice Scarf Gardevoir, but Venusaur will then lack the power to break the opposing team. Life Orb is used to further increase Venusaur's offensive capabilities; the recoil can be ignored, as Giga Drain helps recover from the lost HP. Alternatively, Grassium Z can be used to KO a defensive threat with Bloom Doom, but it is useless otherwise. It is preferred to pair it with Solar Beam, as it gives Venusaur a way to KO a threat once they have been lured in after they realize the Grass-type STAB move is Solar Beam.

Usage Tips:

Always try to switch Venusaur into bulky Water-types, as they lack a way to threaten Venusaur, apart from Air Slash Mantine and Slowbro, and use Growth on the next turn, as they will usually switch out. Giga Drain is the most spammable STAB move and should be used over Sludge Bomb if both KO the foe, as it can recover health. Use Growth on setup fodder such as Florges and Comfey, but be wary of setting up in front of Foul Play users like Umbreon, as Growth also raises Venusaur's Attack stat. Venusaur also draws its checks in, mainly Goodra, Dragalge, and Steel-types, so use that to your advantage. It is wise to save Venusaur until late-game, as it can become a dangerous late-game sweeper. Growth should be usually used on attacks that do not KO Venusaur, as it can just replenish HP with Giga Drain.

Team Options:

Torkoal is a mandatory partner for Venusaur, as it sets sun, which allows Venusaur to fulfill its niche in the tier. Torkoal also helps the team by providing Stealth Rock support, as well as Explosion to weaken threats and give a free switch in opportunity for Venusaur. Ninetales is another option for a sun setter, which itself acts as a setup sweeper, making Sleep Powder Venusaur a preferred choice in that case. But if played in higher tiers Charizard Y is the best choice to use. Chlorophyll users, especially Leafeon, are also good partners for Venusaur, as they can take care of Venusaur's Dragon-type checks, as well as benefit from Chlorophyll. Venusaur also helps Leafeon by taking care of defensive Pokémon. Wallbreakers such as Tyrantrum and Dragon Dance Flygon are appreciated; they resist Fire-type moves for Venusaur and can weaken the opposing team for Venusaur to clean.

Other Options:

Venusaur can utilize a defensive set, but it is outclassed by Chesnaught's utility and Roserade's speed and power. It can also use a Swords Dance set with Power Whip and Earthquake, but its Attack stat prior to setting up is relatively low, and it does not become very threatening even after a boost. Substitute + Leech Seed is also optional, but Whimsicott and Shaymin are better users of those moves due to Prankster and Natural Cure, respectively. Z-Celebrate is an option, but Venusaur lacks both the power and speed to break through the opposing team after the boost.

Checks and Counters:

Dragon-types: Goodra and Dragalge can switch into Venusaur multiple times and KO it with their STAB moves. Noivern and Flygon can take a hit and attempt to KO Venusaur with their STAB moves.

Steel-types: Specially defensive Steel-types such as Registeel and Bronzong take little damage from Hidden Power Fire and can either wear Venusaur down over the course of the game or set up entry hazards.

Gigalith: Gigalith cannot check Venusaur directly, but Sand Stream removes sun, so Venusaur cannot take advantage of Chlorophyll for the rest of the game if Torkoal is down.

Fire-types: Moltres, Salazzle, and Rotom-H resist Grass and can KO Venusaur easily. They also benefit from sun, as their Fire-type moves get stronger.

Moveset:

Defensive: OU
Venusaur (@ Black Sludge)
Ability: Chlorophyll
EVs: 248 HP / 88 Def / 156 SpD / 16 Spe
Nature: Calm (+SpD / -Atk) / Sassy (+SpD / -Spe)
- Leech Seed / Giga Drain
- Sludge Bomb
- Synthesis
- Hidden Power Fire / Earthquake / Knock Off

Moves:

Leech Seed is another option to annoy bulkier Pokemon, such as Celesteela and Toxapex, while allowing Venusaur to further recover HP. Giga Drain is a STAB move that allows Venusaur to check the Water-types that it is supposed to and recovers HP. Sludge Bomb is a more powerful STAB move that can threaten typical Grass-type checks, such as Mega Charizard X, and can be used to attempt to poison bulkier threats, such as Mega Sableye and Zapdos. Although Synthesis suffers from low PP, it is reliable recovery, which allows Venusaur to check opposing Pokemon throughout the match. Hidden Power Fire pressures Mega Scizor, Kartana, and Mega Mawile, preventing them from setting up on Venusaur, and keeps Ferrothorn from freely setting Spikes up. Earthquake can be used to prevent Heatran from coming in for free, as well as allowing Venusaur to better check Magearna. Knock Off cripples potential switch-ins to Venusaur and Pokemon dependent on their items such as Chansey, Alolan Marowak, and Celesteela. Also with Black Sludge you can still have access to Leftovers for another Pokemon.

Set Details:

The given EV spread and a Calm nature allow Venusaur to take hits fromTapu Koko while also outspeeding neutral natured base 50 Speed Pokémon such as Mega Mawile. If choosing to run Earthquake, a Sassy nature is preferred to maximize damage output, and the remaining Speed EVs can be put into its defenses. An EV spread with more Defense and a Bold nature can be used to check Pokémon such as Tapu Bulu and Kartana more effectively, but only if Ash-Greninja is not an issue for the team. Although neither of Venusaur's initial abilities are very useful, Chlorophyll is preferred in order to allow Venusaur to gain an advantage against teams with Mega Charizard Y.

Usage Tips:

Pivot Venusaur into Pokémon that it checks, such as Keldeo and Tapu Bulu, so it can threaten them with its STAB moves or recover its HP using Synthesis. While Venusaur can switch into Greninja some of the time, it has a hard time taking Choice Specs-boosted Dark Pulses from Ash-Greninja or Extrasensory from Protean Greninja. If the opponent has a Greninja, play conservatively with Venusaur by scouting for Extrasensory and by using Synthesis.

Team Options:

This Venusaur set fits better on balanced or defensive teams. Because Venusaur does not have Regenerator, entry hazards can force it to use Synthesis more than attacking. As a result, hazard removers such as Zapdos, Tapu Fini, Mew, and Skarmory make good partners. Steel-types such as Jirachi, Celesteela, and Magearna, which can take on the Flying- and Psychic-types that Venusaur does not like to face, make for nice teammates. Additionally, Pokémon that can take on the Fire-types that Venusaur generally likes to avoid, such as Landorus-T, Garchomp, and Zygarde, make for good partners. Heatran is a particularly good partner because it takes the Psychic-, Fire-, and Flying-type attacks that Venusaur hates, while Venusaur takes Water-type attacks for it. Fire- and Water-types such as Volcarona and Tapu Fini form a core with Venusaur that has good defensive synergy. Venusaur gives free switches to Gengar and Alolan Marowak, so Pokémon that can take hits from these Ghost-types, such as Tyranitar, make decent partners.

Other Options:

A more offensive set with max Special Attack investment allows Venusaur to deal more damage, but also heavily limits its ability to check certain Pokémon like Tapu Bulu and Greninja. Sleep Powder can cripple switch-ins to Venusaur and create opportunities for partners to switch in and use a powerful attack or sweep, but generally, the ability to hit Steel-types or remove items is more useful. Hidden Power Ice prevents Zygarde and Flyinium Z Landorus-T from setting up on it but it does not hit Steel-types. Life Orb Venusaur is one of the best sweepers on sun teams due to its Chlorophyll ability, but sun is generally a poor team archetype.

Checks and Counters:

Psychic-types: Psychic-types like Mega Alakazam, Mega Medicham, and Tapu Lele can OHKO Venusaur with their STAB moves, but many of them do not want to switch into it. Both Mega Alakazam and Mega Latios can comfortably switch into Venusaur and threaten it with Psychic, while both Mega Latias and Calm Mind variants of Mega Alakazam can potentially use it as setup fodder.

Fire-types: Heatran and Mega Charizard Y can overpower Venusaur with their STAB moves while switching into its attacks easily, although Heatran and Alolan Marowak have to be wary of Earthquake.

Flying-types: Tornadus-T, Mega Pinsir, Hawlucha, and Flyinium Z Landorus-T can threaten to OHKO Venusaur with their powerful STAB moves. However, the former two and many others do not like switching into Sludge Bomb, while the third takes a good chunk of damage from Giga Drain.

Chansey: Venusaur's attacks barely do any damage to Chansey. However, Chansey is crippled by Knock Off and Leech Seed, and cannot do much back.

Super Effective Coverage Moves: Since Venusaur only has Synthesis for recovery, it is easily pressured by coverage moves such as Extrasensory from either Greninja and Psychic from Manaphy.