These are the requirements to 100% Punch-Out!! (Wii).
Career[]
The first part of Career is becoming the World Circuit Champion. Start from the bottom and defeat every fighter. (Glass Joe-Mr. Sandman)
After you beat CT Mr. Sandman, You unlock the second part of Career mode, Title Defense Mode. Clear all 13 fighters again in Title Defense Mode. (Glass Joe-Mr. Sandman)
When you defeat TD Mr. Sandman, The final part of Career mode is unlocked, Mac's Last Stand. (You can only lose 3 times before your forced to retire.) Defeat at least 10 fighters to unlock Champion's Mode. (Which makes all punches knock you down in one hit.)
Exhibition[]
Exhibition allows you to fight any of the 13 fighters again. Complete all 3 Challenges for the 13 fighters in both Contender & Title Defense.
The reward for completing the Challenges is audio unlocks. Which has the fighters Fight song, Voice lines & Pain sounds.
Rewards[]
There isn't any rewards for doing 100% itself However, There are some rewards on the way.
Ability to fight every fighter in both Contender and Title Defense as much times as you want.
Audio unlocks for every fighter.
Extra-Challenging Mode in Exabition's.
Non-Requirements[]
These are things that aren't required for 100%.
Unlock Donkey Kong. (Note: There is a chance you can unlock him when doing Mac's Last stand but it isn't required.)
Complete all Exhibition Challenges in Champions Mode.