Its extremely EASY to beat the beasts even at level 3. You need to know your timing correctly and the beasts' attack patterns.
I used Sasuke for beating every beast. Basically, teleporting is crucial .
1st beast - Two Tailed - Attack it, teleport when it tries to swipe you. When it shoots fireballs by leaping away first, dodge.
2nd beast - Three Tailed - most easy beast. Just strike it constantly. WHen its about to do a blast of wind it will pause for a while, then rise up its head. Most of its attacks are easy to dodge.
3rd Beast - The Horned Masked one - Run up, strike it, teleport when it tries to swing at you with its horns. It will tend to rush you and rise up for a while.
4th Beast - The Pig Masked One (or is it bear?) .....working on it. i forgot.
5th beast - The Bear Masked one