TEKKEN 8

If you need to mop these up or you want to do them all quickly:

Load up a vs match against the AI (difficulty on medium), choose whatever characters you want.

If you look at your health meter, there is a section at the end of it, it's roughly the 20% mark, you need to be damaged to get below this threshold. Just let your opponent damage you, on medium the AI will rarely do any combos so there is little danger of them finishing you once you are below the meter. There should now be red flames around your health bar.

Once in this state, ensure the AI is within range and attackable. Press the button to activate the rage art. You will know this has worked as there will be an animation for it, and it should do damage to the opponent (they can block it however, but they rarely do on medium).

Once you've successfully executed the move, press the button and scroll down to level select, select a new level and repeat. You don't need to finish the match.