Meganium

Meganium is outclassed by defensive Grass-types such as Tangela as a physical wall, Roselia as a special wall, Quilladin for utility, and Gourgeist for its typing and physical bulk. It also faces competition as an offensive Grass-type from Leafeon and Sawsbuck, limiting Meganium to a support role. Meganium's defensive sets lack offensive presence as well, making them vulnerable to setup sweepers such as Raichu and Ninetales. Its mono-Grass typing gives it many common weaknesses in the tier, which hinders Meganium's defensive capabilities. Its abilities, Overgrow and Leaf Guard, don't help much. Overgrow is only useful for powering up Giga Drain when Meganium is already at cripplingly low health. Meganium is also highly vulnerable to Taunt.

Nevertheless, Meganium's solid bulk, both physically and specially, combined with average HP makes it a decent, albeit hopelessly outclassed, physical, special, or mixed wall. It is also blessed with good support moves such as Aromatherapy.