The form of God, to which we feel dedicated, should be considered to be the Supreme.
The divine powers of all the living entities are measured through a unit called 'kala'. Starting from the inert matter- rock and minerals, as we move up the tree of life, the number of kalas go on increasing the . The unicellular organisms like amoeba have one kala, plants exist with two kalas while animals have three to four. Average human beings have five kalas while skillful people may have six. Saints have seven kalas while the advanced souls who have higher spiritual capacities may possess eight to nine kalas.
Demigods are said to have ten to twelve kalas and the partial incarnations of God as Lord Parshuram, Lord Narsimha, have divine powers up to the grade of thirteen. Lord Ram, Lord Shiva and Lord Krishna are believed to possess foutreen, fifteen and sixteen kalas respectively. It depends upon the need of time and purpose that how much power would Almighty require to take the avtar with.