Knockout competition, 3 rounds featuring all 8 African nations in the game.
Easiest settings if you just want the achievement with minimal effort: Lowest difficulty, 5 min games, pick a strong team, go 3-0 up then put down the pad and do other things. You'll need to tap a button every so often to take a goal kick, free kick or perhaps kick-off but you don't need to actually play the 2nd half.
A quick glance at the stats for all 8 African nations shows Cameroon and Ivory Coast to be the strongest of the teams.
On the lowest difficulty settings this is hard to loose. I put down the pad to do other stuff after going 3-0 up after 25 mins vs South Africa (3rd/4th best other team), only touching the pad to take goal kicks. Final score? 3-0, they had 3 shots, 1 on target in the 65 minutes of me not playing. The other games I did likewise at halftime. 3-1 and 3-0 being the final scores.