Two planets which have natural friendship with each other, and if any enemy planet is placed in the sign or house of one of these planets, then they will become rivals of each other and this Kundali will be of rival planets.
Enemy planet destroys the results of the house it is placed in and creates conflicts between friendly planets.
In the above mentioned birth-chart, Saturn is debilitated in the first house. Due to the placement of Aries in the first house, its lord is Mars and it is the fixed house of Sun. However, Sun and Mars are friendly planets but due to the placement of Saturn in this house, they will become rivals of each other. In this situation, Sun and Mars will be maleficent for each other.
Similarly Sun is debilitated in the seventh house, which is the fixed house of Mercury and Venus. They are friendly planets, but they will become rivals of each other due to the placement of Sun in the seventh house.