When creating a character, set his heart, power, and speed high. It is important to have the heart to be high. If you jab a lot then throw a punch, it will work much better than just bashing the buttons.

When you get to the screen to set your stats, choose "Heavyweight" then select a height of 6'0" to 6'3" and weight of 200 to 210 lb. Then work on the stats. The most important ones are speed, stamina, heart, and power. Go as high as you can so you can give some and take some hits.