Offense
Offensively, although they are the only type that can super-effectively handle commonly-used Water/Ground Pokémon such as Quagsire, Grass-types have problems in most other situations. The main problem Grass-type moves face is that nearly all of the few Pokémon they are advantageous against are also weak to moves of other types, hence making them seem dwarfed by the effectiveness of moves of other types. Other problems are that too many Pokémon types resist these moves (including themselves) to rely on them as a main form of dealing damage, and most of them aren't very powerful. Even then, most of the powerful moves have drawbacks, which can cause more trouble. For example, Leaf Storm sharply lowers Special Attack, Wood Hammer causes recoil damage, Petal Dance causes confusion, SolarBeam requires charging up if intense sunlight is not nearby and Frenzy Plant requires a turn to recharge after being used. The moves that have no drawbacks, like Power Whip, are very rare. Furthermore, the majority of Grass-types have very narrow movesets, often where the only damage-dealing level up moves are Grass-type and Normal-type moves (as seen in Pokémon such as Meganium, Cherrim and Sunflora). Another problem is that double resistances to Grass are extremely common, even more so than double weaknesses, and the Ability Sap Sipper, which several Pokémon have, negates Grass-type attacks, raising Attack whenever hit with one.
Grass-type Pokémon seem to be affected by weather conditions more than most other Pokémon, due to their closeness with plants and nature. Most power up under intense sunlight, while a few others work best under other conditions, such as Ludicolo in heavy rain, Cacturne in sandstorms or Abomasnow in hailstorms. A majority of Grass types have above-average Attack or Special Attack as well as high Speed, as seen in Sceptile, Leafeon, and Lilligant, which can become mixed, physical, and special sweepers, respectively.
Defense
Defensively speaking, Grass types have both good and bad points. Whilst weak to Ice-type and Fire-type—two very commonly used types offensively—the other weaknesses of the Grass types are rarely used offensively; furthermore, two of the types that specialise in moves that Grass types are weak to are hindered by their poor offensive stats. Also, most Grass types have a secondary type which eliminates their weaknesses to Poison- and Bug-type moves (which in turn makes Flying-type moves more of a threat). Further, all of Grass's resistances are quite common.
On the other hand, Grass types' main problem is their weakness to five types—the most weaknesses of all types (tied with Rock). Also, in practice, Grass types' resistances are still of little use. Almost all Water types can use Ice Beam, and most Electric types can learn Signal Beam. With a number of Grass types being part Poison-type as well, Grass types' resistance to Ground-type moves has been hindered. Given all of this, Grass types are difficult to switch into play.
Despite some of its defensive flaws, it is typical for Grass types to learn Leech Seed and Synthesis, among other disabling moves, like PoisonPowder, Sleep Powder and Stun Spore. This enables these Pokémon to provide support to the rest of their team, and can make them difficult to faint. In addition, a particular asset of this type is being the only one immune to Leech Seed.
Contest Properties
When used in Contests, Grass-type moves typically become Smart moves, but can also be any of the other four Contest types.