What do you think the best starter was in PMD2?
I really don't know. Mudkip pwns all in terms of cuteness and awesomeness, though!!!!!!! <3
What? You want me to judge on how powerful they are? Well, Mudkip, for starters.
And definitely Pikachu, for Agility and Discharge alone (although Thunder Wave, Thunderbolt, Quick Attack, etc. plus Static ability, are all good!); Munchlax, for good evo and moves like Stockpile!!/Spit Up/Swallow, Metronome, and versatility with TMs, being a Normal-type; Skitty, for Cute Charm, Doubleslap, Faint Attack, etc.; Squirtle for balance and good linked move combos; Turtwig for great stats, with above average moves; Piplup for lots of different powerful move types with different effects (Drill Peck, Brine, Dig, Bubblebeam, Metal Claw(upon evolution), Grass Knot, and more); and Treecko for good, 'fast' moves, including AGILITY!!!!!! (Quick Attack, Pursuit, Detect, Giga Drain, Energy Ball, Agility!!!!...)
And since Grovyle has become one of my favorite Pokemon just because of its role in PMD2 (cliche, I know), on Darkness I will not fully evolve it, only to Grovyle. And I'm debating whether to BE Treecko, or have a Treecko partner (LOL, it's your partner Grovyle in the past!! :O).