use a giant slingshot to launch wet sponges at your teammates, who catch them and wring them out into a bucket. The team that fills their bucket with water first, wins. | Could do this by throwing water balloons, too?
Frisbee toss game I made one for our kids and they loved it. I had one basket and put numbers on the bottom of the frisbees. A couple 5's , a 10 and then a 5+1. If they get the 5+1 in the basket then they could choose to take 6 points or take another throw with any one of the frisbees.