Sunny-day teams work pretty wonderfully, as you have your members relying on each other for power-boost and protection. This, I believe, is what makes a team good--crew members depending on themselves for assistance and whatnot. In real life, when working with groups, you usually get help from everyone to make the project successful, and that seems to apply here.
I used to have a sunny-day team, which included Ninetales, Talonflame, Volcarona, Venusaur, Garchomp, and Liligant. Ninetales would set sunlight up with its Drought ability as soon as it gets out to field, then switch to Volcarona. When it's there, it uses Quiver Dance once to boost stats, and takes opponent down with Flamethrower, which gains additional power thanks to sun. Whenever its health is down, it's always able to recover itself with Morning Sun; thanks to sunlight being there, move restores a lot more health than normal.
As for rest, those are there for when Volcarona winds up getting taken down; once it does happen, they all work together to fully knock opponent out.
