If you find that you're really having a hard time winning fights, there's a few things you can do. You can find an opponent that's, well, really inexperienced, such as your little sister or your grandmother, or you can play in the Practice mode. The Practice mode has lots of settings to allow you to fight against an opponent who does nothing whatsoever on up to an opponent who can block your moves, beastorize, break your guard, etc.
Perhaps the first thing to consider is which character to play as. Unlike some other fighting games, this can drastically affect your playing style. Some characters have very simple move lists (such as Xion), others have more involved moves that require 'roundhouse' type movements in combination with button presses to pull off moves (Jenny, Yugo, Alice, Shina, Stun, Busuzima, Bakuryu, Gado), a couple have a single six-level 'chain' plus different 'end moves' to finish the chain (Uriko and Shenlong), and Long's move chart is two-thirds combo rings, with two different six-level combo rings and six different moves to finish a combo. Xion is a good character for beginners to start with. More advanced players may want to try Alice, Jenny, Busuzima, Stun or Bakuryu. Advanced players might want to try some of the combo chain characters such as Uriko, Shenlong or Long.
Additionally, there are many settings which will increase or decrease the difficulty of playing Bloody Roar 3. Difficulty (the obvious one) sets the CPU AI strength and has 8 different levels. Attack Level sets the overall damage level and also has 8 levels. The time limit can be 20, 40, 60, 90 seconds, or unlimited. If you are strong in the beginning of a round and slack off, setting the time limit lower could be in your favor. Match Point is an option that allows you to decide how many matches are required to win the fight. (The default is 2, i.e. 2 out of 3) Match Point can be between 1 and 5.