A method used in Vedic Astrology (Indian). It’s the planet which holds the lowest degrees in the birthchart and becomes the significator of the spouse.
Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn
These are the only planets used for this method.
The Darakaraka gives a description of spouse’s appearance, characteristics and personality. There are several indications in the birthchart that tell you about your spouse, however consider Darakaraka to be extra information to make up the whole picture.

1) Sign placement = Give those qualities to the spouse
2) House placement = Personality has influence of that house, shows the lessons that need to be learned through the spouse.
3) Hard aspects = Gives negative qualities, shows level of suffering in marriage
4) Harmonious aspects = Gives good qualities

Consider the enemy planets of your darakaraka such as the Moon begin an enemy planet to Mercury, in hard aspect it may bring a very moody and argumentive spouse.

Planets as Darakaraka

Sun : Gives an emotionally stable spouse unless it’s conjunct NN or SN. A dedicated spouse with a good status. The aspects the Sun receives in the birthchart are of importance for interpretation such as receiving harmonious aspects from other planets will bring these good qualities to the spouse. If hard aspects are being made such as Mars square Sun it may make the spouse argumentive, competitive or dominant in nature.

Physical : Tall, fair complexion, medium skintone, freckles, amber colored eyes, brown hair, wild, curly or wavy hair.

Moon : Gives an emotional and sensitive spouse who may have moodswings. A possibility of sharing the same moon sign or house placement. But it could also indicate a spouse with Cancerian qualities or a strong Caner influence in their birthchart. The spouse is adaptable to situations and there is a high need for deeper connection. Intuitive spouse.

Physical : Feminine, Curvy (woman) Chubby (man),  short height, beautiful, pale, large breasts (for woman), round face, dark eyes and hair.

Mercury : Friendship, exploration and activities are of importance for the spouse. It’s a good planet as darakaraka since friendship is considered an important part f the relationship. The spouse may be talkative and fond of leisure travel. It indicates a spouse that is younger in age.

Physical : Youthful, medium height, Light hair and eye color, strong cheekbones is possible.

Venus : The spouse could have strong Libra placements in the birthchart aswell as prominent Libra qualities to their personality. A love for comfort and luxury aswell as a need to keep this harmonious and peaceful in the relationship. A spouse who is romantic in nature and perhaps a bit submissive aswell.

Physical : Attractive, beautiful, average, medium height with a bit of curves, Larger breast than average (woman), feminine appearance (man), Dark eyes and hair, tinted skintone, exotic.

Mars : Gives a spouse with a strong will with a strong drive. The spouse will be protective and has a problem-solving approach to life. The spouse is very active on a regular basis such as doing sports. Courageous.

Physical : Athletic, lean, Smaller than average, wide shoulders, small breasts (woman), Bright eye and hair color, tinted skintone.

Jupiter : Gives a spouse with good or high education. Spiritual qualities and an (over) protective nature is possible. The spouse brings wisdom and joy to your life. The spouse loves humor and creativity. Fond of traveling, other cultures.

Physical : Chubby, medium-tall height, endomorphic build, light eye color, pinkish or golden hue skin tone, possibility of being foreign (but not always).

Saturn : The spouse will be (much) older (5-7 years older). The spouse is duty oriented, sober and rather serious. The marriage could have a great longevity and the spouse is determined to work through times of hardship with you. More practical than romantic. The spouse may have strong Capricorn/Aquarian placements in their own chart.

Physical : Strong bone structure, strong cheekbones or sunken cheeks, thick eyebrows, Tall and thin, dark eye and hair color, thin hair, bread, small breasts (woman).