How do you get all three badges in Donkey Kong Country Returns levels?

You get it by earning a bronze, silver, gold, or shiny gold medal in time attack mode. You'll get a better medal the faster you finish a level. All you really need to fill in the circle is to get a bronze medal, which is an achievement to be celebrated. Earning a time attack medal doesn't count toward the percent complete number which is shown on the file select screen. If you want to get 100%, you only have to get all the KONG letters and puzzle pieces.

Thank heaven, as those time attack medals are sadistically, fiendishly, mercilessly, wickedly hard to get.

Good luck!

You can retry the level to run a Time-trial.

Beating the time on the Time-trial version of the level gives the third badge.