The presence of four colours makes it easy to create special candies and is essential as special candies must be used to clear the jellies.
The jellies are worth 16,000 points. Hence, an additional 84,000 points for two stars and an additional 104,000 points for three stars have to be earned through matching of candies.
It is relatively hard to create special candies due to the restricted board layout of only 4 columns. This also mean that colour bombs can only be created via vertical matching.
The jellies can only be cleared using special candies created from the right columns. Moreover, none of the rows and columns where the jellies are have three horizontal or vertical squares. Hence, any huge point cascades is impossible.
The mystery candies may help or harm the player in earning three stars. Given the relatively high two and three star target scores and the above point, it is essential that special candies especially colour bombs appear from most of the mystery candies.