You Select A Region You Want To Start In And Go To An Lab Then Select A Starter
If You Picked Kanto And Are In Proffesor Oaks Lab The Choices Are :
Bulbasaur
Charmander
Squirtle
Pikachu
Eevee
If You Picked Johto And Are In Proffesor Elms Lab The Choices Are :
Chikorita
Cydaquil
Totodile
If You Picked Hoen And Are In Proffesor Birtchs Lab The Choices Are :
Treeco
Mudkip
Torchic
If You Picked Sinnoh And Are In Rowans Lab The Choices Are :
Turtwig
Chimchar
Piplup

Everytime You Finish A League And Go To The Next Region You Can Take Another Starter, You Can Do Them In Wichever Order You Want But You Must Have Done Kanto To Do The Orange Islands And Hoen To Do The Battle Frontier In Your Sig You Must Have A Trainer Card With Your Badges Of The Current Region And Your Pokemon On Team, How Leveling Up, Evolving And Capturing Other Pokemon Is Still To Be Decided, But I Now Legendaries Will Not Be Up For Grabs.