The starter you should choose depends completely on your battle style if you like fast pokemon then you should choose fire types unless you are in hoenn then you should choose Treeko. If you like slow but defensive with high attack choose grass except in hoenn then you should choose Mudkip. If you like pokemon with high defenses or in a couple of cases one defense and one offense then choose water.
The above paragraph was a copy from:thespeedfreak.weebly.com
Slow, High Defence+Attack=Grass(Ruby,Sapphire,Emerald= Mudkip)
I chose Cyndaquil, my bro totodile and my cousin chikorita.
My cousin had to do a new game. Conclusion chikorita is the worst starter.