In R/G/B, you start at your bedroom, and when you try to leave town - having to go through tall grass, Oak shows up and tells you how dangerous it is, and asks you to come to his lab. He gives you your Pokemon.
You reach the next town, and have to go back to Pallet to deliver a package to Oak. You get your PokeDex and you are free to go.
In G/S/C and HG/SS, you go talk to Elm, get your Pokemon, go to meet Mr. Pokemon (was that his name?) - Oak is also there, right?, go back, deliver the egg, get the Dex and is free to go.
In R/S/E, you find Birch being chased by a Pokemon (Poochyena or Zigzagoon), help him, go find your rival, and find yourself back at Birch’s lab, where you get the Dex.
In D/P, you get attacked by Starly, find a briefcase, get the Pokemon in it, defeat the Starly, go back home and then on to Rowan’s lab, where you get the Pokemon and the Dex. (Not sure about this one, haven’t played them yet =/)
In Pt, you try to get into the tall grass, Rowan stops you and gives you the Pokemon. When you meet him at his lab, he gives you the Dex and off you go.
And in B/W you get the Pokemon right in the first scene, at your room. Then you go to Juniper’s lab, get the Dex and sails away.
With this in mind, I’ll come up with a decent start for this game.
The beginning is always hard. To think and to execute. Too much talk, automatic movements, intro, animations… Nothing I an’t handle, though ;P
And I think I know how to start it all.