Most likely you can't just have 6 of your fav qt mons, or your perfect battling team of 6, because you're on a travelling adventure like Ash. You have to think of the practicalities. You'll need to include mons who will help you travel. Big mons to fly and/or surf and/or ride on land on.

So how would you split it? How many practicality-minded travel mons would you have in your party? How many of your fav qt mons would your keep around? How many slots would you reserve for your best battlers?
I'm aware that for some of you, those roles might genuinely overlap
>I wuv my Oddish AND he's my top fighter!
>Gyarados is my top fighter AND he's my choice of sea transport!
>My Altaria is my air transport AND my qtiest cuddlemon!
but for most of us, they probably don't.

inb4
>hurr durr I'll just walk everywhere!
Long and tiring, you'll be left behind as your peers and rivals whizz past you in the game of life.
>hurr durr I'll just travel using proper transport!
There's no public transport outside of cities, nothing connecting towns and various routes and caves etc.
You're not old enough to drive, plus you couldn't afford to have a car.
Plus think of all the battling and experience your mons would miss out on, leaving them weak.
>hurr durr I'll just switch in some mons via PC when it's time to travel, then when I reach my destination I'll switch them back out and bring back in my battlers, then I'll switch them back out for travel mons on the way to the next place
Lame, you won't bond well with your mons when they're only around you some of the time, especially if you constantly switch them in and out. They'll probably become very unhappy with that instability, which will affect their development and willingness to listen to you. Pokemon are kinda like children, they need a consistent stable 'family' dynamic that fosters trust and love. Like Ash and his mons.

So, team of 6. And describe why you include them, what their roles would be. Go!