Venus is just the opposite and inimical to the Mercury. hence the sign in which Mercury is exalted Venus is debilitated and vice-versa. Since Mercury is exalted in the 6th sign i.e. Virgo, Venus is debilitated in the Virgo while Mercury is debilitated in the 12th sign i.e.  Pisces

Venus is exalted in the Pisces upto 27 degrees. and debilitated in the Virgo upto 27 degrees.

Jupiter: Jupiter is considered a hot, sanguine, airy, beneficial, masculine planet. He rules over watery sign Pisces and fiery magnetic sign Sagittarius. A native in Jupiter will be tall, well built, handsomely proportioned.

Jupiter is the planet opposite to Mars planet. hence it is debilitated in the sign where Mars is exalted i.e. in Capricorn. Adding 6 signs we get Cancer where Jupiter is exalted.

Jupiter is exalted upto 15 degrees in Cancer. and is debilitated upto 15 degrees in Capricorn.

Saturn: Saturn is the most distant planet from the Sun. He completes his revolution in 29 years. Saturn signifies prudence and caution. The aspect of Saturn implies obstacles and delay.  The influence of Saturn is most dominant during the first thirty years of life.

As per hindu mythology Saturn is the son of the Sun but is opposite of the Sun hence it is debilitated in the sign where the Sun is exalted i.e. Aries and the Saturn is exalted in the sign where the Sun id debilitated i.e. Libra.

The Saturn is Exalted upto 20 degrees in Libra and debilitated in Aries up to 20 degrees

Rahu: In Indian Astrology Rahu is a shadow planet which is evil, tamsik  and unfortunate planet in nature. Rahu always moves retrograde and is friendly with Saturn, Mercury and Venus. It is known as Dragon’s Head in western Astrology.

Rahu was the name of Trijata ( 3 plaited monstrous) hence 3rd sign i.e Gemini was the exalted sign of Rahu.Adding 6 signs it is Sagittarius,  hence Sagittarius is the dign of debilitation for Rahu is exalted in Gemini upto 15 degrees and debilitated upto 15 degrees in Sagittarius.

Ketu: Ketu is the shadow planet and is considered as the shadow of planet Mars. It is always positioned 7th from the Rahu as it remains 180 degrees from Rahu. This planet is considered to be the karak of Moksha and is the planet of sudden happenings and incidents. Ketu is always retrograde same as Rahu.

Since ketu is placed 7th from Rahu hence the exaltation sign of Rahu is the debilitated sign of Ketu and the debilitated sign of Rahu is the exalted place of Ketu.

Ketu is Exalted in Sagittarius upto 15 degrees and is debilitated in Taurus up to 15 degrees.