Dad, Jim Powell, has super strength, invulnerability and leaping. He can lift 11,000 pounds (maybe more), has been run over by cars repeatedly without sustaining injury, and can leap up to 1/4 of a mile with a single jump, although his landings are often not very graceful. However, he is vulnerable around the nape area of his neck.
Mom, Stephanie Powell, has super-speed. She can run over 700 mph (maybe more). While moving fast, her reflexes are similarly enhanced as if she is paying attention, other things seem to be frozen in time to her. Her super fast metabolism causes fast digestion so she needs to consume a lot of food. She also displays rapid healing due to her high metabolism.
Daughter, Daphne Powell, can read minds. Further into the series, this evolves into seeing the events that happened to the person she touches as if she was in their shoes. Eventually, she also develops the power of persuasion, though it does not have any effect on her brother JJ.
Son, JJ Powell, has super intellect. He can instantly solve complex math equations, understand complicated theories and such. The extent of his powers is not completely explored but it is assumed he will be able to apply the knowledge and perhaps have enhanced memory.