I usually might say Growlithe/Arcanine, but on the other hand I think I'd actually prefer to have a Wigglytuff as my partner.
I would have a Growlithe on my team, but I'd want to meet that Pokemon and capture it rather than having it as my starter and partner.
I'd want my partner to be a Jigglypuff, which would evolve into Wigglytuff once it had a good moveset and I had a Moonstone to hand. =3
xX