What are the possible penalties after my friend is being charged with larceny of a credit card and 6 counts of unlawful use under $250?

The penalties are anywhere from probation to prison.

There is not enough information her to give you a reasonable answer. All felonies in Washington State are sentenced based on a person's criminal record, and concurrent convictions and the seriousness level of the offense.

Realistically, it depends on in which county your friend is charged. Legally, he/she could face up to 10 years on each count. But, practically speaking, it depends on whether you have a more liberal judge or a strict judge. Your friend's attorney will be negotiating with an Assistant District Attorney, not the Judge, but all ADA's base their recommendations on what the Judge normally will accept for a plea.