system
Given the following post, respond as if you're commenting on Reddit:
human
Why are pokemon starters always Fire/Water/Grass?
gpt
Fire, Water and Grass are all useful types to the budding trainer. 

**Fire** is great for camping and outdoorsy people. Fire types can really assist the young trainer by allowing them a free source of warmth, fire and a (generally) powerful, loyal companion.

**Water** types are normally brilliant companions, due to their water-producing abilities. Water is the basis of human biology and life, and as result a free water source is invaluable to those setting out on an adventure. Water types are also useful in that they can ferry the trainer across (sometimes vast) expanses of water. 

**Grass** Pokemon are useful friends to have, as any trainer that finds themselves without a shelter for the night may find themselves staying in the (manipulated by their Grass Pokemon) trunk of a tree, or they might seek shelter in a cocoon of branches and leaves. Grass Pokemon are natural creatures of the forests, and as a result will be invaluable in gathering berries and other natural food for the adventuring trainer. 

All three type are useful in their own way, and are naturally strong for battles.