1. Importance of different planets in horoscope keeps changing with time. So understand a very simple ideology before you get pampered or scared with any planet/planetary combination in your horoscope.
2. At the outset, let me clarify that no horoscope will have only good or bad planets.
3. Any planet in any house, be it strong or weak, does not give any results on its own.
4. Role of different planets in horoscope theoretically remains the same.
5. Importance of different planets in horoscope varies as the person grows in life. So it is better to understand the role of any planet at a particular stage of your life. You will understand as you read further down.
6. Most importantly, the result of different planets in the birth chart depends on how you negotiate with the planets with your Free Will/Karmas.
7. Planets are in the horoscope, and horoscope is what you get when you are born. The planets in horoscope are based on the position of planets in the Constellation at a particular moment when you are born.
8. This particular moment of birth is decided by Lord Brahma. How Lord Brahma decides this is all based on the balance sheet of your own Karmas of the previous birth(s). So in a way, you yourself craft your horoscope, which is allotted to you by the Supreme Power.
9. Normal perception is that out of 9 planets, some are enemy planets, and some are friendly. Let’s take one example: If Mars is friendly to Sun, it is an enemy to Venus. A friendly Mars can be helpful when you need him for your career or when you need authority. But the same Mars (Mangal) can act harmful when you need good results from Venus (marriage, love, and romance). So it depends on what stage you need Mars to help you be aggressive and passionate and at what stage Mars can harm you.
10. Strongest/most favorable planet, if operating at lower energy, may not bestow the inherent good results associated with that planet. In the same way, most negative planets, if operating at lower energy, may not give you harmful results for which it is known.
11. So when we talk about planets in horoscope, their role remains the same; importance of planets in the horoscope change with time, and results from the planets depend on how we do our Karmas.