The players.
More specifically, the 11th Edition rules for Ultimate state:
XVI. Violations and Fouls
H. Fouls (II.E): It is the responsibility of all players to avoid contact in every way possible .
1. A foul can be called only by the fouled player and must be announced by loudly calling foul immediately after it occurs.
In the sport of Ulimtate Frisbee, there are no referees. Players must call their own fouls and etc. The game relies heavily on good sportmanship and the ''Spirit of the Game''
The spirit of the game in ultimate Frisbee is that you follow the rules and play fair. Since there are no referees in ultimate, is is up to the players to call their own fouls and travels. Spirit of the game is that you will not cheat and you will go out their and play fairly. After the game, you will be respectful and not brag or boast.
Ultimate Frisbee is the correct way to spell it.
There are no referees. The players call their own fouls
Frisbee golf
Ultimate Frisbee is most popular in New Zealand and the United States.
No, you do not have to win by two in Ultimate Frisbee, just first to 13 or whatever you are playing to.
I wouldn't say 'national championship' but the professional sport of frisbee is 'ultimate frisbee'.
Ovbiously
Ultimate Frisbee is the 'football-esque' version of frisbee, but there is also disk golf.
The handler in Ultimate Frisbee is responsible for throwing the frisbee to another player, called the cutter. The handler is an offensive position much like a quarterback in football.
Ultimate Frisbee Ultimate Fighting Championships