What effect does the score have in Kirby: Mass Attack?
Solution 1:
After the end credits when you've beaten the game, it will show many statistics, one of which being your grand total of points (from all stages added up). I had over 2 million points, apparently.
So it's just a statistic, good for bragging rights I guess, like with most Mario games. You get several other statistics too after the end credits!
Solution 2:
After reading through the manual, searching online, and my playtime in the game I can safely say score serves no purpose in Kirby: Mass Attack.