Venusaur

Venusaur is one of the most threatening Grass-types in the metagame, almost forcing every team to carry a check to it. Its Mega Evolution is one of the bulkiest Pokemon around, with impressive defensive stats of 80 / 123 / 120. Mega Venusaur is also a perfect counter to rain, walling the most common rain sweeper, Ludicolo. In addition, it perfectly fits into a bulky Fire / Water / Grass core, and its Poison typing allows it to solidly beat Fairy-types, as it resists their STAB type and hits them super effectively. Regular Venusaur can also work well as a sun sweeper thanks to Chlorophyll. However, Venusaur struggles with its limited coverage outside of its STAB attacks, having only various Hidden Powers as options for better coverage, and its weakness to Flying- and Psychic-type attacks, especially Talonflame's priority Brave Bird. Fire and Ice are also weaknesses, but these are neutralized when Venusaur Mega Evolves.