Purple: Whisper- Level 4
Red: Gordon- Level 4
Green: Temper- Level 7
Blue: Howie- Level 7
Yellow: JoJo- Level 4

For the box, I started from the sides rather than top to bottom. Red, Green and Blue had side combo powers.Try to do as many Yellow Combo's before the 3rd slug as he is immune to Yellow Combo's, that way you can use the other color combo's to get him down. Afterwards try to really watch how many moves you have left and which color has the most combo's in the least amount of moves. However I did pay the gold bars since I was one move from finishing the level. Hope this helped!