"ready to rumble" is a correct and usable phrase in written English. You can use it to show that someone is prepared and eager to engage in something, especially if they anticipate a challenge or competition. For example: John entered the room, ready to rumble with his opponents in the big game.
And we're ready to rumble".
Let's Get Ready To Rumble".
Get ready to rumble.
The Cubans are getting ready to rumble.
Boxing is ready to rumble again.
Rand is ready to rumble.
Mr. White is ready to rumble.
Let's get ready to rumble.
"He was ready to rumble".
You are ready to rumble.
And get ready to rumble...enter today!
Being a terminologist, I care about word choice. Ludwig simply helps me pick the best words for any translation. Five stars!
Maria Pia Montoro
Terminologist and Q/A Analyst @ Translation Centre for the Bodies of the European Union