this is taken straight from the Guidelines:
Bijuu mode:
-If u have zero health you cannot activate this.
-This only lasts 6 turns and can be activated once per battle
-When you activate this your health and chakra are both increased
-If u havent beaten ur opponent after using your sixth turn you lose.
-It will only be used as a last resort and only the original characters that posses the bijuus in the manga/anime can use it.
-There will be no one tail-9 tail mode but only one mode,bijuu mode.
Bijuu mode:
-If u have zero health you cannot activate this.
-This only lasts 6 turns and can be activated once per battle
-When you activate this your health and chakra are both increased
-If u havent beaten ur opponent after using your sixth turn you lose.
-It will only be used as a last resort and only the original characters that posses the bijuus in the manga/anime can use it.
-There will be no one tail-9 tail mode but only one mode,bijuu mode.