Ant-Man's powers and abilities
As Ant-Man and Yellowjacket, Henry Pym possessed the power to reduce himself to the size of an ant, approximately one-half inch in height, by means of the subatomic particles known as the Pym Particles. The nature, source, and mechanics of the Pym Particles remain unrevealed. Originally, when Pym inhaled a gas or drank a potion containing the Pym Particles, the Particles would interact with the electrical impulses of his brain, creating an organism-wide "reducing field." Thus activated, the field reduced his entire body at a uniform rate to the smaller size he desired. Although he usually chose to reduce himself to one half inch in height, he could reduce his size to any size between that and his normal size. Usually, Pym did not compress his mass into his smaller size. Instead his mass was somehow extended into an extra-physical dimension that is opened by the activating of the Pym Particles, from which the mass could later be reclaimed. Strangely, because Pym's mass was extended extra-dimensionally when he was at ant-size, he retained his full human-size strength at that size. To return to normal size, Pym inhaled another gas or drank another potion, either of which contained another type of Pym Particles. These particles interacted with his brain to create an organism-wide "enlarging field," which is energized by mental command. Thus Pym could grow back to his normal height and reclaim all of the mass that was extended extra-dimensionally.
Too many size changing within a short time span can be fatiguing. Growing to gigantic sizes is more of a physical and mental strain and switching directly from giant size to insect size or vice versa is particularly taxing. Pym's most recent modifications to his powers may have included a variation on the additional mutation that he induced in Van Dyne years ago, which harnessed the energy of her size-changing process and used it to enhance her strength, presumably easing the physical strain of size-changing. Pym's strength, stamina and upper size limit in giant form all seem to have increased by comparison to his earlier giant-size since he became the Wasp.
Entering other Planes of existence
Pym sometimes used the Pym Particles to shrink to sub-microscopic stature. When 99.99 + % of his mass was extra-dimensionally shunted, he was sent into a "subatomic universe" or "microverse," one of countless alternate universes accessible to Earth only by the mass-shunting process. Such as shrinking down to enter the Microverse, and on one occasion growing into the plane inhabited by such cosmic beings as the Living Tribunal and the In-Betweener.
Mutated by Pym Particles
Continuous exposure to Pym Particles over an extended period of time enabled Pym to generate his reducing and expanding fields spontaneously, without exposure to a new quantity of Pym Particles. Hence, Pym could increase or decrease his size simply by will power.
Pym has the normal human strength of a man of his age, height, and build who engages in intensive regular exercise. He retains this level of strength even at insect-size.
Scientific Genius-Level Intellect
Dr. Henry Pym is one of the world's foremost biochemists and also possesses considerable expertise in numerous scientific fields such as subatomic physics, robotics, cybernetics, programming, emergency medicine, optics and entomology. His high I.Q. makes him one of the nine smartest people in the world capable of rivaling others such as Reed Richards and is regarded by the Eternity as the Earth's "Scientist Supreme".
Hank is a skilled hand-to-hand combatant using special styles of unarmed combat depending on his size. If he is small, he takes advantage of the opponent's larger form by assaulting points of his/her body that they would not expect and move to another before they detected him. If he was giant, he would take advantage of his own massive form and use attacks that would either throw them off balance or render them unconscious before they could concoct a better strategy against him. Has had some training in judo, karate and wrestling. He was also trained by Captain America in unarmed combat making him a very formidable fighter. A trained scuba diver. Capable pilot of aircraft ranging from conventional helicopters to high tech vehicles such as the Avengers Quinjets.