Pokémon Diamond and Pearl/Lake Verity

Once you go to Lake Verity you will see Dawn (or Lucas, depending on which gender you chose) and a professor standing and talking at the shore. They will thereafter exit, politely asking you to move aside so they may do so. Your rival notices that they left behind a bag of some kind. He says there's no harm in going into the grass for a second to see what's in the bag. That turns out to be wrong, as you are attacked by a, at level 2 which you have to defeat.



Starter Pokémon Choices
To fend off the Starly, you are given a choice of three Pokémon: Piplup, Chimchar, and Turtwig. Piplup is a great starter for defensively minded players, as its evolved form, Empoleon, has resistance to 12 of the 17 types. Turtwig, although not especially powerful, is easy to raise. Chimchar is hard to raise, but is a great attacker. It would also be good to note that Chimchar is one of the only 5 fire Pokémon in the pre-National Pokédex era, and since three of those five are in the Chimchar family, and the other two are in the family, there is a shortage of Fire types.

Watch the cutscene, and you'll be forced onto the tall grass, and into a battle. THIS IS WHERE YOU CHOOSE YOUR STARTER

Choose whichever one you feel is the best or your favorite, as they will all help you in your journey. You should easily defeat the Starly with your new-found Pokémon.

The Battle
Keep slamming it with attacks until it's killed. Each of the starters start with a damaging move (Scratch, Tackle or Pound) and a stat reducing move (Growl or Leer). Starly should be defeated fairly easily.

After the Battle
After you defeat the Starly (and gain some Exp. Points), the Dawn/Lucas will come back to fetch the briefcase, and sees that you both took a Pokémon each. (S)he is worried about explaining this to the professor and rushes off. You will exit to the lake front and head back to Route 201