Grass-type moves are neither the most powerful nor the most common moves among non-Grass type Pokemon. However, there are still a number of exceedingly useful Grass-type moves that are worth learning.
The usefulness of Grass-type moves does not only come from their sheer power but also from other advantages that they can provide to the player. Synthesis, though not on this list, is an excellent example of this. It heals 50% (depending on the weather) of its user's maximum HP with no downside.
Note: This article is subjective and reflects the opinion of the writer.
Best Grass-type moves in Pokemon
#5 - Leaf Blade
Leaf Blade is a high-damage physical Grass-type move available to a wide variety of Pokemon, including a few notable heavy-hitters like Gallade.
This is one of the most viable physical Grass-type moves due to its stable accuracy and power. It is well-known due to the Treeko family tree's use of it.
#4 - Giga Drain
While not quite as useful for competitive play, Giga Drain is a boon in casual play. It is an easy and reliable way to top up your Pokemon's HP without having to dip into your items or spend extra time running back to a Pokemon Center.
However, that's not to say that Giga drain is only useful for healing. The healing is just a nice bonus to the already decent damage the move can deal.
The biggest downside of Giga Drain is how little PP it has. However, the amount of damage it deals while healing the user makes the move worth it.
#3 - Energy Ball
This special Grass-type move has the same base power as Leaf Blade, but its special effect of lowering the attacked Pokemon's special defense is arguably better.
In addition, a wider variety of Pokemon can learn Energy Ball, making it one of the most common and readily available options for both Grass and non-Grass type Pokemon.
#2 - Spore
Spore is one of only two moves in the entire franchise that is guaranteed to put the opponent's Pokemon to sleep while also having 100% accuracy. The other move, Relic Song, is exclusive to Meloetta - a Pokemon that many casual players have never even seen in-game.
The only reason why Spore is only number 2 on this list is that only three families of Pokemon can learn this move, and none of them are particularly great at it.
#1 - Solar Beam
Solar Beam is an exceptionally powerful move, having 120 base power while also maintaining 100% accuracy. Unfortunately, the player needs to spend an entire turn charging the move up, giving the opponent plenty of time to prepare a countermeasure. This is an exception when it's nice and sunny. When Strong Sunlight is pouring down, Solar Beam activates instantly, destroying the opponent with no side effects whatsoever.
Solar Beam is number 1 on this list because of its popularity as a move in various Pokemon media. It is also the biggest saving grace for the popular Sunny Day team composition.
A good number of Fire-type Pokemon can learn Solar Beam, making it the perfect counter to those pesky Rock and Ground-type Pokemon that work so well at stopping Fire-types that have been powered up by the sun.