At first glance, Vileplume seems to be absolutely inferior to Venusaur. She shares the same great typing yet loses out on a multitude of movepool options (namely, Power Whip, Leaf Storm, Earthquake, and Roar) and possesses poorer base stats (barring Defense, every base stat is less than or equal to Venusaur's). However, the little rafflesia still has a few advantages over Venusaur—most notably, Aromatherapy. Aromatherapy differentiates Vileplume from Venusaur and gives her the ability to function as a sturdy cleric with some special bulk. Like Venusaur, Vileplume also gets the valuable Sleep Powder, and somewhat reliable recovery in Moonlight.
Vileplume's main problem is that she is easily walled by Pokemon with a decent amount of special bulk. While such Pokemon do not stop Vileplume from accomplishing her main job as a cleric, they can simply set up against her while she struggles to damage them. In addition, Vileplume has an extremely shallow offensive movepool, as the only special moves she has are Grass- and Poison-type moves.
Vileplume's main purpose is to heal her teammates of status by using Aromatherapy. While Meganium first appears to be a better candidate for the job due to her superior defenses and access to Reflect and Light Screen, Vileplume avoids being outclassed due to her secondary Poison-typing and access to Sleep Powder. Energy Ball allows Vileplume to take a chunk of health from bulky Water- and Ground-types, while Sludge Bomb aids Vileplume in defeating Sceptile, who could otherwise set up Swords Dance or Substitute, and Venusaur, who takes pitiful damage from Energy Ball. The last moveslot is up to personal choice. Moonlight is Vileplume's only instant-recovery move, but it is troubled by poor PP in comparison to other instant-recovery moves. In addition, its recovery has the unfortunate side effect of being halved under rain, hail, or sandstorm. Leech Seed is an alternate form of recovery that enables Vileplume to serve as an acceptable annoyer. Sleep Powder allows Vileplume to essentially remove one of the opponent's Pokemon from play if it does not have Sleep Talk, Natural Cure, or the rare Insomnia.Team Options & Additional Comments >>>
Vileplume has a few interesting moves in her very limited arsenal. Stun Spore and Teeter Dance could be used to run a parafusion set that hinders the opponent's ability to fight back. However, such a set is better in the hands of Lanturn, who can do the same but with Thunder Wave, which is 100% accurate. Toxic aids Vileplume in combating Milotic, although Energy Ball already does sufficient damage to her. Charm can be used to lower the Attack of physical sweepers, but has limited usefulness due to Vileplume's low Speed.
Vileplume's offensive options are extremely few in number. Grass Knot is an interesting option, doing more damage to Rhyperior, Milotic, Donphan, and Regirock than Energy Ball. However, it loses much of its power against lighter threats, particularly Omastar and Azumarill. Vileplume can choose to run a physical set (with Body Slam and Seed Bomb as her attacking options), but it lacks much power and has poor coverage.
Checks and Counters
Most of Vileplume's counters do not take away her ability to heal her teammates, but instead force her out with their STAB moves. Fire- and Flying-types such as Arcanine and Swellow fall under this category; however, these Pokemon must all watch out and be careful not to switch into Leech Seed or Sleep Powder. Vileplume also has problems with Pokemon who enjoy setting up on weak attackers. Calm Mind Mismagius and mono-attacking Registeel and Spiritomb take little damage from Vileplume's attacks and can bypass Sleep Powder by using Substitute and Sleep Talk, respectively. However, these Pokemon also do not enjoy being struck by Leech Seed.