These teams are usually intended for competitive battles (not defiant battles :P). US is an old game, so it might be difficult to find opponents in that game. If you want to battle opponents using US game mechanics, then it's usually easier to go to Showdown!, click the box under "Format:", click "[Gen 7] OU", build a team, and click "Battle! Find a random opponent".
Drizzle: usually set up by a Pelipper, used by offensive waters (like Swampert and Greninja), fire-weak Pokemon (like Scizor and Ferrothorn), and hurricane users (like Tornadus)
Drought: usually set up by a Charizard, used by offensive fires (like Victini) and rarely a chlorophyll user (like Venusaur)
Sand Stream: usually set up by a Tyranitar, used by sand-immune walls (like Celesteela), sand rush users (like Excadrill), and regenerator users (like Tangrowth and Toxapex)
Toxic Spikes: usually set up by a Toxapex, used by defensive and passive Pokemon (like Chansey, Sableye, and Gliscor)