There are the Grass type Pokémon that has the pure and half-type for the Pokémon species.

For example:

The first pure Grass-type is Tangela was the Vine Pokemon and then Victreebel and Vileplume are the Grass/Poison type was mixed as the half-type.

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Automerged:
Just like we said there are the starters of Grass-type Pokémon are Venusaur, Meganium, Sceptile and Torterra.

Speaking between of such amongst various Pokemon form species, of aqua type. Mixed of aqua and sand such exist. Which is types that can play swim or play swim half-species.

For example:

The first Water-type is Quagsire. Is mixed-species full-type.