I just transferred an out of state title and registration to Massachusetts. Boy, oh boy, are they specific. You need the original title for sure. They take that and issue a new one. They will also take the old registration. If you purchased your car < 6 months, make sure you have proof of sales tax payment in the form of it being checked on the registration. They wouldn’t accept the original bill of sale stating that. Luckily I had to go in once and it was quick. FYI I went to RMV in Wilmington. Super smooth. No appointment needed.