Starter Pokémon

At the beginning of their quest, Trainers are given a starter Pokémon, usually at the first town where the Trainer lives. This Pokémon will be used to battle the Rival and the first wild Pokémon that the Trainer encounters.

Mechanics
Once another Pokémon is caught, the starter Pokémon may be retired, but it cannot be released or traded in any way. As such, even advanced Trainers may still use their starter Pokémon, and they will often be the most powerful Pokémon on their respective teams.

These Pokémon are known to be able to learn a wide variety of moves and have generally high base stats.

It is said that the starter Pokémon are extremely rare in the wild, giving the player a reason why the Pokémon not chosen can't be found in the wild easily.

Average total base stats: 525-534

Kanto
In the Kanto region Professor Oak will bring Trainers to his lab to give them one of the following Pokémon to begin their journey with:

Johto
Currently, starter Pokémon from the Johto region can only be obtained in Hoenn Safari Zone.

Hoenn
In this region, the player will find Professor Birch on Route 101, chased by wild Pokémon. After he is rescued, he allows the player to keep the Pokémon they chose to rescue him with, either:

Sinnoh
Here, when two Starly attack the player and rival at Lake Verity, to which they travel upon hearing reports of a red Gyarados, they will choose one of the following from Professor Rowan's briefcase, which he left at the lake:

Unova
In Unova, Professor Juniper leaves a gift with the player's Mom in Nuvema Town to give to them, containing the following three Pokémon:

Unobtainable
While these Pokémon are currently not yet in game, they deserve an honorable mention as starter Pokémon: