Now the game is over, I will attempt a better response.
WA's max jail penalties for fighting is 10 times higher then Idaho's 1 year. IF you get the max in Idaho, which is doubtful.
You may spend a night or two in jail to cool off. But getting a full year would be very rare, and only in violent unprovoked attacks.
The local DA and judge rarely put anyone in jail for long periods, unless it is murder or sex with a minor. Then they throw away the key. It cost too much to keep people in jail for minor offenses, and that includes being found guilty of selling illegal drugs.
Idaho's max fine for fighting is $1000. The max fine in WA is also 10 times higher.
If it is an unprovoked attack, you will be charged.
Then it gets down to who provoked who, how, and what are their past records. So one, both, or neither might get charged for fighting. It's up to the local officer to make the call.
If found guilty of fighting in our county, a $50-100 fine is the norm. You can get 10 years and a huge fine in WA for the same thing.
BTW, we have very few fights. Mostly drunk fights in bars. The county only has about 4-6 jury trials per year, for all offenses. Our crime rate is much lower than OR's & WA's. Another reason I moved away from Vancouver to here.
And so you know, the last fight I was in was about 50 years ago. But there are a lot of people around Portland/Vancouver that badly needed a trip to the woodshed for a tuneup. Not sure I had much patience left by the time I moved from that shithole area.