Well, I'm kind of indecisive here - Charmander's my favourite starter overall, but I'd rather start from the Johto region. I'll do up two different scenarios for this...
Region: Kanto Region
Reaction: Well, I'm finally doing it. The day I've been anticipating for the longest time has arrived. What'll it be like, raising my own Pokemon and battling other trainers in real live matches? What Pokemon will I end up catching and raising? I have so many questions, but so few answers. I'd best find someone to travel with and help me out for the first bit of the trip...
Starter: Charmander
Travel With Others: Yes, I'd probably travel with at least one other person.
With Who: I wouldn't mind traveling with Misty, and maybe a grass-type trainer. There are a number of characters from the anime I'd like to travel with, but out of all of them, I think I'd prefer most to travel with Misty.
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Region: Johto Region
Reaction: Oh gosh, do I have everything I need? Johto's a highly forested place, so I'll need to pack plenty of supplies for camping in the woods from time to time. Oh, and I'll need my camera, too... and my... oh, I think I'd better do up a list before I set off...
Starter: Sticking with the fire-types here, I'll go with Cyndaquil...
Travel With Others: For parts of the journey. Other parts I'd rather explore on my own.
With Who: Gold and Crystal from the Pokemon games (or their anime counterparts, Jimmy and Marina).