Pokemon Dream Radar which can help you speed up on the collection of Dream Orb (Can use them to restore all of the dream clouds 3 times a day for a total of 15 coins).
And since I'm going to restart the game a couple more times (So that I can transfer all 8 Legendaries to Pokemon Black 2/White 2 and from there transfer them to the origina Black & White), I'm definitely going to stock up on some coins.
Sonic Generations. Never going to get 100% because I ain't wasting my stockpile of coins for some measly missions. It's a shame, I really wanted to see what songs made it into the 3ds version. --- I'm just dickin aroouunnnd SHAKE AND BAKE!