Assume you were going to go on a journey across a fairly unpopulated mostly uncharted continent and are allowed 1 pokemon to take with you. Which do you choose?

Pokeballs don't exist in this universe so you pokemon follows you of its own will. No legendaries are allowed and you can only choose the most basic evolution, it can evolve though. Realistic physics apply in battle and the continent is full of wild hostile pokemon as well as people unbound by law who may try and kill you.