What is better/faster ? Take the boy or the girl, and why?
What is the better pokemon starter ? I see a lot of mudkip.
The girl is faster because of the Rival 2 fight. Grovyle is Rash, which makes it easier to kill with Echoed Voice.
Mudkip is better because Mudkip can easily deal with Roxanne first of all. Then the Ground typing helps a lot against the Electric and Fire gym. Also Bulldoze is available really early on which also drops opponents' speed by one stage, which is helpful multiple times.
I recommend joining our Pokémon Speedrun Discord to get more answers as these forums are fairly dead: https://www.speedrun.com/pkmnoras/thread/5ggs8
Wartab covered pretty much everything as far as character selection, but i would like to chip in by saying you should name her ! Because 1 character is fastests, and ! is the fastest character. However you should not name your mudkip because the time gained by naming it ! is not enough to make up for the time loss to go into the naming menu, unless a new route is made that allows you to beat the game with just your starter (and hm slaves)