Venusaur
Ranking: A+ or S-
Ability: Chlorophyll
Item: Black Sludge
Moves: Leech Seed, Sleep Powder, Petal Dance/Double-Edge/Hidden Power Fire/Giga Drain (egg move), Growth/Nature Power
Why: Venusaur learns two great moves for stalling purposes in a Grass monorun, Leech Seed and Sleep Powder. With this strategy, Venusaur can slowly chip away at the foe's health while maintaining a relatively high health. In addition, Venusaur also has access to Chlorophyll allowing for a speedy Sleep Powder. With Chlorophyll, Venusaur can also run an offensive set with Growth. The primary weakness with Venusaur is that it has a hard time dealing with Grass types if it does not have Hidden Power Fire. If Venusaur had access to Sludge Bomb, it would definitely be in S rank.
Exeggutor
Ranking: B
Ability: Chlorophyll
Item: TwistedSpoon/Rose Inscense
Moves: Extrasensory, Sleep Powder, Leaf Storm/Seed Bomb, Nature Power/Trick Room/Explosion
Why: Exeggutor has an above average Attack stat of 95 relatively high Special Attack stat of 125. This Special Attack stat tends to be used more often due to a wider Special moveset. However, physical attacks such as Explosion can be quite helpful as well. In addition, Exeggutor has a pretty solid HP and Def stat. However, what sets Exeggutor back are its low Sp Def and Speed stats, and 4x weakness to Bug, often causing it to be outspeed and OHKOed with a Bug Buzz. Chlorophyll is used over Harvest because there are not much berries Exeggutor can take advantage of, and Chlorophyll can sometimes be helpful in outspeed Poison types and hitting them with Extrasensory.