Import rules are national not state based, and I'm pretty sure WA has not seceeded yet.
If it does not have a compliance plate it came in under:
1. personal import
2. 15yo import (before it was shut down)
3. race rally import.
if you do not know which scheme it came under, DOTARS who approve all imports will. Also WA's car rego department must know as well. 1 and 2 are eligible for full rego, 3 is not.