Kommo-o and the Unknown Darkness!

[Famon]

According to Kommo-o official entry

There is a legend that says Kommo-o is covered in glittering scales in order to drive away a great darkness covering the world. The reason these Pok?mon seek out battle is to gain the power needed to defeat this darkness.

What is this great unknown Darkness that Kommo-o trying to defeat ?
At first , I thought it to be Marshadow or any other Evil Ultra Beast .
But , Marshadow doesn't look like a threat and Ultra beast aren't covering the world since they comes from another dimension.
Could it be a hint for another New Evil pokemon that pose a great threat to the world in Future game ?

I also like to point out Kommo-o connection with Slivally.
Both pokemon and their pre-evolution was revealed at the same time in the same source.
Both Pokemon are suppose to fight a Great threat .
We know that Type Null and Silvally were created to fight Ultra Beast.
But , Whom does Kommo-o Suppose to fight ?
Necrozma ?

 

[User19sq]

Or it could just be referencing Ruy from Street Fighter. Fighting? Check. Dragon motif? Check. Darkness of some sort? Just look up "Evil Ryu".