If there is one thing you can admire Venusaur for, it is the sheer number of sets it can run. Not bad for the first fully evolved Pokemon in the Pokedex right?
Sunny Sweeper Saurian
Ability: Chlorophyll
Item: Life Orb
Nature: Timid (+Speed -Attack)
EVs: (HP 4) (Sp.Attack 252) (Speed 252)
Moves:
Sunny Day
Solar Beam
Sludge Bomb
Weather Ball
Set Details:
Might as well make the most of Chlorophyll as Venusaur's ability. Set up Sunny Day to boost your speed and supplement your offensive moves. Solar Beam becomes a one-turn attack in the sun, Weather Ball gets boosted twice over and becomes a Fire attack for coverage, and Sludge Bomb offers secondary STAB and good overall neutral coverage with poison support. Invest everything into special attack and speed, and use Life Orb to shore up your damage output.
Sub-Seed Saurian
Ability: Chlorophyll
Item: Black Sludge
Nature: Bold (+Defense -Attack)
EVs: (HP 252) (Defense 156) (Sp.Defense 100)
Moves:
Substitute
Leech Seed
Sleep Powder
Giga Drain/Sludge Bomb
Set Details:
Your standard Substitute and Leech Seed set. Seed your opponents and then hide behind Substitute as your opponent's health is drained to feed your own HP for future Substitutes. Sleep Powder is useful to make your opponent useless by forcing them to either waste turns or forcibly switch out, and the last move is an offensive move of your choice with Giga Drain offering additional HP recovery and Sludge Bomb offering additional damage and the chance to inflict poison. Invest in HP and your defenses, slap on Black Sludge to increase your survivability, and have Chlorophyll as your ability so you can outspeed your opponent in the sun.
Sword Sweeper Saurian
Ability: Chlorophyll
Item: Black Sludge
Nature: Jolly (+Speed -Sp.Attack)
EVs: (HP 4) (Attack 252) (Speed 252)
Moves:
Swords Dance
Power Whip
Earthquake
Sleep Powder/Sunny Day/Body Slam
Set Details:
While Venusaur's special attack is higher, it's physical attack is not terrible and has the potential to be boosted further unlike its special attack by setting up Swords Dance. Power Whip is your main offensive threat backed by your STAB, Earthquake handles many targets that Power Whip cannot hit hard with barring Flying types, and your last move is a matter of preference. Sleep Powder offers status support and an easier time to set up Swords Dance, Sunny Day capitalizes on Chlorophyll allowing you to outspeed the opponent, and Body Slam offers neutral coverage with a chance of paralysis as a bonus. Venusaur is still bulky even with its stats invested into attack and speed, so Black Sludge still works wonderfully with this set.
Sinister Stalling Saurian
Ability: Chlorophyll
Item: Black Sludge
Nature: Bold (+Def -Att)
EVs: (HP 252) (Def 156) (Sp.Def 100)
Moves:
Toxic
Protect
Synthesis/Giga Drain
Earth Power/Venoshock
Set Details:
A Toxic stall set since Toxic has become increasingly rare with the removal of its TM status. Inflict Toxic and then stall for damage and Black Sludge recovery. From there you could slap on Synthesis as your recovery move, but if the low PP and weather dependency is a turn off you could sub in with Giga Drain which offers HP draining and better offensive presence. Earth Power offers coverage against the Poison and Steel types that are immune to Toxic, but if again you want a more offensive moveset you could use Venoshock which doubles in power on your Poison targets allowing you to knock them out sooner. Once again, invest everything into HP and defenses.
I Ran out of Alliteration Set Names
Ability: Chlorophyll
Item: Black Sludge
Nature: Careful (+Sp.Defense -Sp.Attack)
EVs: (HP 252) (Sp.Def 252) (Speed 4)
Moves:
Curse
Synthesis
Power Whip
Earthquake/Body Slam
Set Details:
A physical tank set. Use Curse to boost your physical attack and defense, use Synthesis to heal as your gradually boost up, hit hard with Power Whip, and then use either Earthquake of Body Slam for general coverage. Invest everything into HP and special defense since Curse already has you covered in the physical defense department and keep Black Sludge as your held item for additional HP recovery.