The plural of "battle royal"

[Sky]

I've never been able to get a straight answer to this. All three answers have their benefits and drawbacks:

• Battle royals is the natural way of saying it, interpreting "battle royal" as a single two-word noun. For some reason, though, this feels wrong to me.
• Battles royal assumes "royal" is an adjective and modifies the noun "battle". Notably, this is the way Wikipedia claims the correct pluralisation is. It might confuse people though.
• Battles royals is a sort of compromise that's derived from interpreting it as a foreign language phrase (from the alternative spelling used outside of wrestling, "battle royale"). "Battles royals" would result from a language that has adjective-noun agreement. This feels the least natural in my opinion.

I decided to throw this open to the forum - which is the definitive correct spelling? (The result of the poll will be canon)

 

[Chris]

Battle Royals.

When it became a match type it became a noun so it follows noun plural rules

 

[Spitfire]

Never the last one.

 

[Moon Bird]

I'd say the plural is the same as the singular.

 

[Spitfire]

I believe its Battle Royals

or Battles Royale

if you use the Royale spelling

 

[Marty McFourth]

I think I've always said Battle Royal

 

[Marty McFourth]

So, none of the above I guess

 

[Comrade Khan]

Battle royals

 

[Kiffy Lube]

World War 3.

 

[Alexa]

Using English rules Battle Royals would be the proper way of saying it. Battles Royals is an abomination of God