Venusaur is my favorite of the three Kanto starter evolutions.
Unfortunately, Venusaur ex from 151 is mid.
Fortunately, I have spent a lot of time to craft a Venusaur deck that isn't terrible. That being said, I welcome any input or suggestions in the comments! Thank you!
The idea is to get Hisuian Lilligant onto the Active spot as quickly as possible to power up a Bulbasaur using Swelling Scent, then evolve to Venusaur ex and move to active and you're ready to go.
Because Venusaur ex's Dangerous Toxwhip poisons the opponent's Pokemon, you will want Radiant Hisuian Sneasler on your bench for the Poison Peak ability to rack up more damage.
Take advantage of Gardenia's Vigor to quickly energize Venusaur as well.
One important note: When I've played this deck, very often I am able to set up two Venusaur ex with full energy within a few turns. Combine Venusaur ex's Tranquil Flower ability with the Hero's Cape, and Venusaur is really hard to knock out from the active spot. With a second Venusaur ex on your bench and you can use Tranquil Flower to heal 60 hp then switch/jet the other Venusaur into active and heal the other 60 hp. Brutal!
Anyway, hope this helps the Venusaur fans.