Levels 5 and 8 have a bug where all you need to do is win to beat it. The difficulty should be like this, imo:
Easy: 1, 2, 3
Medium: 4, 5, 9
Hard: 6, 8, 11
Ultra: 7, 10
Almost Impossible: 12
Level 12 advice: If you concede first, restart. Go right at the beginning. Losing the header will make you concede everytime. Time your jumps (+ kick at the peak of your jump) so that you make the ball go UP. The rest is luck. The AI will often kick the ball over the goal, and hopefully bounce to their own goal. This is how I got 90% of my goals.
HOLY SHIT. THE AI IS SO RIGGED. I win by over 4000 points, and the AI for the last roll gets FOUR FREE ROLLS IN A ROW, beating me by 1000. Complete bullshit. I haven't won a single game yet, and I've played 7 times.