I choose base on cuteness and profit for those starter
Kanto:Charmander(overate but so useful in this region)
Jotho:Cyndaquill(I thought Chikorita might be good...I was wrong I can't even get pass Falkner and Quilava look cool :3)
Hoenn:Treeko(because I want May to have Torchic...that it)
Sinnoh:Turtwig(I like to start with Piplup but then rival would win,I don't like monkey,and I want Dawn to have Piplup)
Kanto:Oshawott(OSHAAAAA!)
Kanto:Chespin(I think you know why)