As a Paramecia type, the user has the ability to transform body parts into durable pieces of oak. On top of that, they can create oak not attached to their body. This is useful not only for offensive and defensive abilities on the battlefield, but for practical everyday uses (firewood, lumber for cabins, etc.).
If the user is near trees, they can manipulate the trees to their will, rather it be shape-shifting the trees or removing giants chunks of the tree.This gives the user an advantage if the battle takes place in a forest or jungle, as trees are scattered about everywhere.
One of the biggest drawbacks to this Devil Fruit is that oak is highly flammable. This makes the user take much more damage against fire-based attacks such as Flame Dials or Sabo's Mera Mera no Mi. Since Fleet Admiral Akainu's Magu Magu no Mi is higher up on the Logia chain than Sabo's Devil Fruit, magma-based attacks do far more lethal damage than fire.
If the opponent can break through material more durable than oak, then the defense is nearly useless. This can prove to be a disadvantage against tough bare-knuckle brawlers like Luffy and Garp. As well as swordsmen who have easily cut through more durable materials such as Zoro and Dracule Mihawk.
Oak (or any wood) not taken from trees require energy from the user to create. The larger the amount of oak created, the more energy it will cost. If too much oak is created, the user could collapse due to over-exertion.
While oak wood is very durable, it is merely a blunt object when used in combat compared to swords, knives, and guns. As a result, killing someone with the oak-created weapons would be very difficult and merely act as a tool to knockout the opponent rather than execute them.
Aside from the weaknesses stated above, the user is also weak to Sea Prism Stone and being submerged and water, rendering their powers useless.
Bokushingugurōbu (Boxing Gloves)- The user creates boxing gloves for added strength in punches.
Roddo (Rod)- The user creates a rod for combat.
Kurasshu (Crash)- Similar to the Barrier Crash technique by Bartolomeo, the user creates a wide chunk of oak, then lunges it at the opponent.
Bokkusu (Box)- The user traps the opponent in a box made of oak. They could either use this as a chance to retreat, or fling the box around, damaging the opponent inside.
Bariaringu (Barrier Ring)- The user creates a giant ring of oak to shield themselves and possibly others around them from giant attacks. Since it is a ring, however, there is a giant hole in the top, making themselves vulnerable to aerial assault.
Kabe (Wall)- A giant, durable wall of oak shields the user from an incoming attack. Similar to Mr. 3's Candle Wall.
Pasu (Path)- A sheet of oak is used to create a path over large gaps that would be impassable.