Whether to have an attorney is up to you. The Washington state court expects you to follow the procedures just as an attorney would if you represent yourself.
There are plenty of persons sitting in jail or prison who were convicted of their first offenses, including misdemeanor assault.
The lowest assault charge under Washington state's statutes is "Assault in the fourth degree" which is a gross misdemeanor. In WA, the maximum punishment for a gross misdemeanor is up to a year in jail, $5000 fines, or both. (A misdemeanor's punishment is up to 90 days in jail, $1000 fines, or both.)
While cities and counties may have their own charges and punishment, the cities and counties usually simply copy the state's statutes.
If you are low income by local Pierce County standards, you have the right to a public defender who is an attorney paid by the city or county. In many cities and smaller counties, public defenders are private attorneys who take on public defense cases.
Pierce County and Tacoma have public defender associations whose only job is public defense.
Absolutely YES you should get a lawyer to learn the specific ramifications for you, the risks, and the alternatives on how to approach the charge of misdemeanor assault in Tacoma.
A conviction for assault in the fourth degree, a gross misdemeanor, carries a sentence of up to one year in jail and a $5,000 fine in Washington. Usually a person does not get that sort of time on a first offense of misdemeanor assault. A court may impose any sentence up to that year, however.
More important than the sentence are some of the long-term "collateral" effects of a conviction for assault. It can disqualify you from many jobs that include close work with children or vulnerable adults, i.e., teaching, nursing care, child care, etc. It also can be a basis for deportation if you are not a United States citizen.
If you are convicted of Assault in the 4th degree, the maximum penalty is 365 days in jail and a 5,000.00 fine. If it is against a friend/roommate or family member, the punishments may be even more severe -- likely causing your right to own firearms revoked. It is always advised that a person in your position contact an experience attorney who will fight for your rights and who isn't afraid to challenge the State's evidence. I am a young and aggressive attorney who will fight for you!