Healing,
Poison Manipulation,
Death Manipulation and
Reactive Evolution with
The Deathdealing (Yhwach can control over any and all 'Lethal Doses' within his range. He alters the dosage of any substance he ingests or tanks, manipulating the 'poison' and either granting himself complete immunity within a single minute or lowering an opponent's resistance to kill or incapacitate them. Furthermore with Askin's Vollständig, Hasshein. Yhwach will automatically adapt to changes in "poison"; as long as the base of the poison remains the same, any surface layer changes will cause Yhwach's immunity to adjust in turn, rendering the poison ineffective)
Superhuman Physical Characteristics,
Invulnerability,
Size Manipulation (Other Celestialsapiens can easily grow to the size of a galaxy),
Flight (Easily flies across interplanetary distances),
Reality Warping (Easily recreated the universe with a simple thought),
Immortality (Types 1 and 3),
Regeneration (Mid-High),
Body Control,
Forcefield Creation,
Telekinesis (Moved and threw the Amalgam Kids),
Duplication (Created many copies of himself in his fight against
Galactic Gladiator),
Multiple Personalities (In order for Alien X to perform any action, including simple movement and transforming back, all three of his personalities must agree to do so. His personalities include Serena, the "voice of love and compassion", Bellicus, the "voice of rage and aggression" and
Ben Tennyson, the "voice of reason"),
Space-
Time Manipulation (Serena stated that Alien X can change the very nature of time and space),
Mind Manipulation (Controlled the Amalgam Kids' minds to make them fight each other),
Pocket Reality Manipulation (Serena, Bellicus and Ben Tennyson hold absolute control inside Alien X's body, which is a pocket universe that contains many galaxies),
Nigh-Omniscience (Recreated the entire universe in exact detail, but with a few minor changes ex: the Mr. Smoothy logo and Ben wearing a new jacket),
Acausality (Type 2),
Skilled Hand-to-Hand Combatant,
Self-Sustenance (Types 1 and 3),
Cosmic Awareness,
Teleportation,
Summoning,
Portal Creation,
Creation,
Black Hole Creation,
Information Manipulation,
Fire Manipulation,
Existence Erasure (Stated by Servantis that with a Celestialsapien form,
Ben could one day wipe everything out of existence)
I was going to answer Mid-Godly Regen, but apparently Yhwach have only Low-Godly