Having a friend buy it and transfer it to him is definitely not legal under federal law.
1. He can buy and transfer through an FFL in Oregon
2. He can just go buy one in Oregon.
3. He can establish residency in WA. Note that for federal purposes, you can have more than one state of residence and be legal to purchase firearms in each state. Not sure how documentation works for that.
My sense is that he's not very serious about this. Oregon is a short weekend or a long day trip away from Seattle.
DON'T LET YOUR FRIEND'S LAZINESS SADDLE YOU OR ONE OF YOUR FRIENDS WITH A FELONY CONVICTION!
Tell him to take a road trip already or quit whining.