Easy Knockdown: When your opponent is approaching you at the beginning of the initial fight use your special power punch which will stagger him. When he approaches you again hit him with another special power punch and then attack him with a combination of body punches. Keep attacking him and his strength will then drop until you have knocked him out.
Career Mode Development: First max out your speed then your strength. This will be useful in matches because all you have to do is continuously throw hooks until your opponent is dazed. When your opponent is dazed use your Super Punch to knock him down. Use this technique to knockout all your opponents.