The Metatrix gives Ben the powers of every single alien in the Codon stream and their Ultimates with the abilities enhanced times fifty. Ben can use any alien's abilities, even all at once in any form, human or alien. He can also transform any part of his body into that of any other alien or Ultimate he desires. He has enough power to take out an army of Ultimate Way Bigs, seeing as has the strenght of more than 100 Ultimate Way Bigs not to mention his duplication and other enhanced powers.
Ben first gets the Metatrix In Ben 10: Meta Menace to fight MetAggregor after he takes the Omnitrix and absorbs all the power from it (all the aliens were unlocked) making him unstoppable enough to exact his revenge on the Levin/Tennyson family.
MetaBen also wears Forever Knight armour with the Metatrix symbol (a blue hourglass with the green infinity symbol behind it) on his chest and the sword Ascalon which was sealed into the Metatrix in a sheath on the left side of his waist.
MetaBen has also mastered his anodite powers as well as magic
All these traits combined made him virtually the most powerful being in the Ben 10 universe, especially seeing as Diagon was still sealed within Ascalon . Although Ben eventually battles him again after his essence drives MetaBen insane.
After defeating Diagon , MetaBen regained his sanity and fixed the damage he had caused. Although, he needed to be nudged in the right direction by the presence of his teenage self as well as teenage Julie, Kevin and Gwen.
After Aggregor breaks out of jail, he finds Ben and kidnaps Julie (who is pregnant and married to Ben) and forces Ben to give up the Omnitrix for her. After doing so, Azmuth presents his latest and greatest invention to Ben, the Metatrix. Ben uses its powers to defeat Aggregor and continued to use it to keep peace until the essence of Diagon in Ascalon (which is in the Metatrix) overwhelms him and he slowly becomes a menace, up to the point where he becomes just as insane as Ultimate Kevin , until Paradox brings the young Ben, Gwen, Kevin and Julie to snap Ben back to his senses, after which he unleashes Diagon and battles and defeats him thereby vanquishing him. Azmuth then allows Ben keep the Metatrix.
After Meta Menace
Ben makes a Metatrix for Julie, making her MetaJulie, much to Azmuth's annoyance.
He also conquered the Forever Knights in a duel with King Adam, thereby making the knights his own personal army.
Here, Ben's son Rex is now a teenager and is now mature enough to fight off aliens. Prior to the series, from Rex's 10th birthday, Rex has had an Omnitrix (the Evolutrix) which he has been using to fight criminals, and starting from his 15th birthday, he became ready to fight true evil.
MetaBen and MetaJulie play passive roles in this series, only appearing when Rex has no other chance of winning.
POWERS AND ABILITIES
SUPER STRENGTH - Due to the enhanced powers of Humongousaur, Ultimate Humongousaur, Way Big, Ultimate Way Big, Terra, Ultimate Terra and others
SUPER SPEED, FLIGHT, AND AQUATIC RESPIRATION- Due to the enhanced powers of Jetray, Ultimate Jetray, Xlr8, Ultimate Xlr8, Fasttrack, Ultimate Fasttrack, Ripjaws, Ultimate Ripjaws, Stinkfly, Ultimate Stinkfly and others and enhanced. He is fast enough to travel at around the speed of light, taking off at supersonic speeds.
PYROKINESIS - Gotten from Heatblast, Ultimate Heatblast, Swampfire, Ultimate Swampfire, NRG, Ultimate NRG and others and enhanced. His pyrokinetic skills at full power have been proven to be hotter than the sub-surface of our sun.
TELEKINESIS- Gotten from Brainstorm, Ultimate Brainstorm, Brainiac, Ultimate Brainiac and others and enhanced. He has enough telekinetic strength to uproot and lift the entire city of New York and more.
CRYOKONESIS - Gotten from the enhanced powers of Bigchill, Ultimate Bigchill, Arcticguana, Ultimate Arcticguana, Iceray, Ultimate Iceray and others. He is shown to be capable of freezing a small star or an entire planet solid.
SIZE ALTERATION - He is able to shrink to the size of a speck or grow to the size of a planet. His strength still remains unphatomable despite his size.
GHOST-LIKE POWERS - He has invisibility, intangibility, possession e.t.c
META DURABILITY - Gotten from the enhanced powers of Water Hazard, Ultimate Water Hazard, Way Big, Humongousaur, Cannonbolt, Diamondhead, Chromastone and their Ultimates.
TELEPATHY - He has the ability to read minds, control minds and send mind messages. Gotten from the enhanced powers of Brainstorm, AmpFibian, and others and their Ultimates.
SHAPESHIFTING - Not only can MetaBen transform any part of his body into that of any other alien, but thanks to some shapeshifting aliens like Chronomorpho, Ben can take literally any form, thereby being able to imitate anbody.
SUPERSENSES- Gotten from the enhanced powers of Wildmutt, Benwolf and others and their Ultimates, MetaBen can sense a specific rat a continent away (no offence Argit).
SUPER INTELLECT - Gotten from Brainstorm, Grey Mattter, Benvicktor, Brainiac, others and their Ultimates. MetaBen proves to be smart enough to even challenge Azmuth and even claims to be smarter, something which Azmuth will not admit.
ANODITE POWERS - MetaBen has trained alongside Gwen under Verdona and her siblings and is far more advanced with his anodite powers even far more than 16 year old Gwen.
MAGIC - He, as well as Gwen have trained under Charmcaster in the arts of magic.
PLANT POWERS - From Wildvine, Swampfire, others and their Ultimates. MetaBen has supreme control over plants as well as creating them.
TIME CONTROL AND MANIPULATION - Gotten from Clockwork and others and their Ultimates.
MULTIPLICATION - Gotten from Echo Echo, Ultimate Echo Echo ( all these Ultimates are just a bigger, stronger, faster version of the originals, this is my design of the Ultimates), Ditto, Buzzshock and others and their Ultimates. The clones share a telepathic link and know what is going on with each other, but even if you kill one ( good luck with that ) the others will still live.
ELECTROKINESIS - Gotten from Brainstorm, Benvicktor, Buzzshock, AmpFibian, Shocksquatch, and others and their Ultimates. In one fully powered blast, MetaBen can generate enough electrical power to power the cities of Los Angeles and Las Vegas for a week at least. He can also summon lightning due to Weather Master.
SUPER EATING ABILITIES - Gotten from Upchuck, and others and their Ultimates
HYDROKINESIS - Gotten from Water Hazard and others and their Ultimates. MetaBen can control water like Percy Jackson or Poseidon. Even being able to absorb moisture from air and solidify water into a form of 'warm ice'.
MAGNETISM - Gotten from Lodestar and others and their Ultimates. MetaBen can magnetize all sorts of metals even non-ferrous ones.
REALITY WARPING - Gotten from both his anodite heritage and 's personality. MetaBen can warp reality to the very whim making him omnipotent.
REGENERATION - Gotten from Swampfire, Goop, others and their Ultimates. Ben can regenerate from any bit, be it an eye or a finger or a toenail clipping (ewe)
SPEAKS ALMOST EVERY LANGUAGE
TECHNOLOGICAL CONTROL (this includes the upgrade touch)
MATTER CONTROL AND MANIPULATION
POWERFUL THEN THE GALAXY LORD RAX,GUARDIAN GODS AND THE GOD FORM (Imad 10)
travel between universes
unconscious causality and probability on a multiversal level
enhanced senses and perceptions on a vast cosmic scale
matter manipulation and deconstructon