Gremmy Brain Ability

The Visionary:

Subjective Reality & Reality Warping (Thought-Based - Gremmy can turn his imagination into reality with The Visionary)

Stealth Mastery (Gremmy can use The Visionary to sneak behind two high ranked Shinigami with ease)

Death Manipulation (Gremmy can imagine an opponent's death and cause that to happen in reality)

Transmutation (Gremmy can turn his opponents bones into cookies by imagining it, causing them to crumble)

Elemental Manipulation & Sealing (Gremmy can manipulate the ground beneath him to construct a battlefield, create lava, imprison his opponents in a cube of water, to drown and suffocate them)

Nonexistence Erasure (Nature: Types 1 & 3, Aspect: Types 1 & 3 - Gremmy can erase objects and people from existence through his imagination. This erasure is potent enough to erase Guenael Lee from existence despite the fact he's completely unaffected after erasing his very own existence from reality with "The Vanishing Point", with his "existence" containing his soul, mind and body)

Weapon Creation, Weapon Control & Explosion Manipulation (Gremmy can additionally create rifles and missiles to attack his opponents)

Healing (Gremmy can heal his wounds by simply imagining them healed)

Adhesive Manipulation (Gremmy can make his body sticky to immobilize his opponent)

Danmaku & Earth Manipulation (Can create a massive hand to attack his opponent. Gremmy can further manipulate the earth by creating large pillars that can attack from all directions)

Metal Manipulation (Can create a metal dome to shield himself and form blades from this dome)

Statistics Amplification (The Visionary can be used to enhance Gremmy's durability and strength)

Life Manipulation, Duplication & Creation (Can create an exact duplicate of himself through his ability to create life and this clone doubles his imaginative powers. Gremmy with this clone can create a meteor which even after Gremmy's death will still exist)

BFR, Portal Creation & Pocket Reality Manipulation (With several clones, Gremmy can create outer space, open a portal to it and throw his opponent into it)

Self-Destruction (Gremmy's clones can be detonated at will along with himself)

Power Bestowal (Using The Visionary, Gremmy is capable of granting himself and others new abilities, like those of Guenael Lee)

Resistance to:

Paralysis Inducement (Ranso Tengai allows Quincy to freely manipulate their bodies using spirit energy if their bodies would be inflicted with great physical harm or paralysis)

Possibly Resistance to:

Mind Manipulation & Empathic Manipulation (It is said to be the brain of the Soul king, so it must have been created from Oken.)