Personally, I would either use the Turtwig or go for Axew. The others don't really seem like they'd be too helpful later on for the reasons Etesian listed.
Turtwig has a rough start, but naturally learns earthquake upon evolving into Torterra at lvl 32. There's also Curse, Leech Seed/Synthesis, Wood Hammer(from the move relearner in Sheridan), etc. The point is: Torterra is awesome.
Charmander, I'm more hesitant about recommending. Its level up pool is very limited. It doesn't learn any special non-fire type moves(aside from Dragon rage) without TMs or the move relearner. It can't even learn Air Slash without a heart scale.