you can only use Pokémon that are the same color as the flag of the country you live in

https://bulbapedia.bulbagarden.net/wiki/List_of_Pokémon_by_color

which do you pick
(if the country has an even distribution of colors, you can either 1) pick one color, or 2) make a team of various colors as represented by the flag)
otherwise if your flag is mostly one color, use that

This is such a creative thread! The colours may not exactly match with those of Bulbapedia's.(Why's butterfree in white)

Here's the tricolor:
I'd love to make a team of various colours. I can make a team that has the following colours: White, Orange, Blue, Green. This team might not be good from a competitive standpoint , though.
1: Abomasnow - white
2: Garchomp - blue
3: Sceptile - green
4: Talonflame - Orange
5: Greninja - blue
6: Absol - white

So since I'm from the states, I can use Red, White, and Blue for my colors. The team I'd pick from it would be:
1) Froslass
2) Togekiss
3) Krookodile
4) Samurott
5) Salamence
6) Braviary

I've only got red and white to pick from for Canada, and to be fair, I'll use the proportions of the flag to make up my team (2/3 red, 1/3 white), otherwise my team would probably be 5 white and 1 red lol

Red
Rotom-W
Incineroar
Scizor
Porygon-Z

White
Froslass
Gardevoir

As I'm from the UK, I've got Blue, Red and White to use - divided into 3 pairs of pokemon.

Blue
Hydreigon
Greninja

Red
Porygon Z
Darmanitan

White
Froslass
Togekiss