how about NOT making the 3 starters Fire, Grass and Water, lets make em...

Rock, Ghost, Bug ya

I can't come up with any ideas for names n such. But how about a grass-type, water-type, and fire-type?

A new three-way set. Like Psychic, Dark, Fighting.

There's no other three-way set that has the resistance and weakness that Grass, Fire and Water have.

That would be inbalanced as Dark is immune to Psychic attacks.

There are elemental triangles that do not contain the types: Grass, Fire, or Water! Psychic, Dark, and Fighting is one (thank you Mr Khan!) and the other is Steel, Ice, and Ground. But they are not as well structured as Grass, Fire, or Water.

Thank you! The names take time to get used to, even though they maybe slightly tedious. 

Flamingo?!
Hell no, Reptiles (or mammals by that matter)>birds.
It's why torchic was a fail imo.
We need a fire starter that later becomes fire/dragon.
Speaking of which, why the hell is charizard not dragon?
ok enough nerd rage.

Because he/she would be too powerful!

Thank you! I think SmokedHostage has forgotten the tradition of the Grass type being the slowest but with the highest defence that was broken by Treecko and its evolutions.

Then it could be balanced by giving it a 4x Weakness by creating a Dark/Ice starter.

I actually like the idea of a new three-way set. It won't have the same resistances and weaknesses of the used Trio, but that's the entire point. Game Freak can tweak the balance by giving us new pairings or some pairings that can keep the same balance.

Or, ultimately, they could change the Battle properties as they did in II generation. Who's to know?

In the end though, the most logical conclusion is that it's going to stay Grass, Water and Fire.