General Challenge event tips?

[DragonSnake]

Pirates Corellia New Challenge Event

first time playing this challenge, any advice to get the higher score possible ? colors stacking ? rainbow ? battle items usefull to get higher score ? I will do only rare, i only have two 4* and they arent maxed, only at 3/60 so i guess its not possible to complete legendary with only 2 4* ? ( its chao and colen)

Good source of info