Well lets say so far we seen two types of abilities that a non Devil Fruit User can have that can make him equal or greater than Devil Fruit Users. In some cases Devil Fruit users have these abilities also making them much stronger than normal Devil Fruit Users and enhancing their power sometimes.
There is the
The 3 Haki
Kenbunshoku Haki - sixth sense of the world around them and limited precognitive abilities
Busoshoku Haki - spirit as armor for defense or to make their own attacks more potent
Haoshoku Haki - the ability to overpower the will of others
and the
The 6 Rokushiki
Kami-e - users' body go limp in order to avoid any attacks, and float like a piece of paper
Geppo - allows the users to actually jump off the air itself
Rankyaku - icking at very high speeds and strengt causing an air blade that can slice objects
Shigan - Finger Gun using their finger leaving a wound similar to a bullet wound
Soru - allows the users to move at extremely high speeds
Tekkai - hardens the users' muscles to nullify damage
added to that there are
3 types of Devil Fruit
Paramecia - power which can affect their body, manipulate the environment or produce some kind of substances
Zoan - allows the user to transform into another species and inter-species hybrid forms at will.
Logia - giving its user the ability to turn into a natural element or force of nature
Now if a person had full use of the 3 Haki and was also skilled in the 6 Rokushiki and also ate one of the Devil Fruits most likely a Logia type would he be nearly invincible.
There is the
The 3 Haki
Kenbunshoku Haki - sixth sense of the world around them and limited precognitive abilities
Busoshoku Haki - spirit as armor for defense or to make their own attacks more potent
Haoshoku Haki - the ability to overpower the will of others
and the
The 6 Rokushiki
Kami-e - users' body go limp in order to avoid any attacks, and float like a piece of paper
Geppo - allows the users to actually jump off the air itself
Rankyaku - icking at very high speeds and strengt causing an air blade that can slice objects
Shigan - Finger Gun using their finger leaving a wound similar to a bullet wound
Soru - allows the users to move at extremely high speeds
Tekkai - hardens the users' muscles to nullify damage
added to that there are
3 types of Devil Fruit
Paramecia - power which can affect their body, manipulate the environment or produce some kind of substances
Zoan - allows the user to transform into another species and inter-species hybrid forms at will.
Logia - giving its user the ability to turn into a natural element or force of nature
Now if a person had full use of the 3 Haki and was also skilled in the 6 Rokushiki and also ate one of the Devil Fruits most likely a Logia type would he be nearly invincible.