For 3 fairly easy golds, even if you are kind of a mediocre arcader like myself, buy Crystal Castles and start a ranked game.
*** edit *** They only need to be bronze medals, but all 3 golds are easy on this games so that is why I picked this game.
~On first screen go to the back of the play area in the corner and you will find a secret jump spot. Press A to jump here and you will immediately get your gold medal out of the way ;)
~ The hardest part is Surviving 6 minutes. For this you need to start a new your game, wait til all 3 enemies have come around the corner, then run around to the jump spot and sit there. When the hornets come down about the 5th time they will try to land on you. Run around in a big circle til they get you.Do this 3 times and on the last time use your jump point. Go to the left elevator and go up and wait. Do this again for your extra life and you should just manage 6 minutes.
~ Now just repeat the above til you have 3 shiny golds ;)