Overworld: use the arrow to move Mario, A two jump. Battle: use the left and right arrow keys to select your move then use A button to use your move, and use the L Button to cancel a move. Tips: if you pick the jumping move, while jumping click the A button as soon as you touch the enemy, if you pick the hammer move, while charging up your hammer click A at the right time to do more damage, but if you wait to long it will about 6 to 11 damage. If you pick flee, you will automatically go back to the beginning, and finally if you pick the item slot, you will be able to pick to pick to use a super mushroom, or a syrup jar.
all credit goes to Nintendo and @SpidyPlaysMC