Oh man, this is hard. Let me think. I guess I'll go with Blue? I'd love to go for Orange to incorporate Arcanine and Green to incorporate Meganium and Celebi, but Lucario, Blastoise, and Lanturn makes three Blue members, and Togekiss is the lone White in my top six.
Blue, final answer. Lucario, Blastoise, Lanturn, Alolan Sandslash, Jumpluff, and Altaria would be my team.
Serperior (good ability - contrary)
Alolan Muk (dark/poison is a good combo surprisingly)
Xatu (can be reuniclus but that flying type is useful)
Golurk ... is green...? wow i just noticed that now (like the others ground and ghost provides good coverage)
Araquanid (ooh this pokemon is good gotta have it. bonus points for good typing)
Fraxure or Flygon (just wanted a dragon type but flygon may deem golurk unnecessary)
that team was fun to build! i should try a colored run :D
Was bored, so I decided to make teams out of each of the official Pokedex colors (even though some of those aren't as accurate as they should be). Didn't include shiny Pokemon, or put Pokemon in a different category even if they clearly should be.