1) To make obtaining this and all other achievements faster go to options and turn speed play on
2) Custom play ->Battle -> Two players -> select location (no need to change default location)
3) Select human for player 2
4) With player 1 (you) roll dices and try to fill lower section squares (damage). "3x", full house and short straight are easiest to obtain. If you can't use damage square then just heal yourself. You can also use "?" square and have 1/3 change to damage player 2, but beware as it might damage you instead.
5) With player 2 roll dices once and select any square with “-“ mark. If any of those squares aren’t available, roll again.
6) Continue until player 2 has no points left and then you can start new game right away.
I suggest that you complete adeventure mode first and then classic, rainbow, duplicate and battle modes until you have unlocked Classic master, Rainbow master, Duplicate master and Battle master. Then check your stats for Victories (Extras -> Statistics). You should have around 40 victories. Then if you start with Battle mode, you should unlock Battle sensei at around 80 victories. If you jump from mode to mode, you can't keep track how many victories is needed before achievement unlocks.