newer sprint phones require flashing yes, old phones such as your average decade old flip phone they will activate for you if you get a live person on the phone and make them do it, but only after the account is active and to create an active account you must.use a boost phone
to be quite honest i have borrowed boost esns to activate accounts before, you only need it till you switch to the sprint phone
that all being said, no android phone is cobsidered a legacy device by sprint therefore you cant get it active no matter how hard you try. it would take changine the meid which is legally questionable but as long as you use an android donor to activate an android phone i dont personally see the issue, and data will require you to use the donor phones data connection usernames and passcodes stored in nv items 465, 466, 1192, and 1194. galaxy prevail is a possible donor, i even wrote a program to do most of the work for you as far as the data thing but you still have to be tech savvy