Generally we can have a single user with DBA rights to import/export (using imp/exp utilities) data into any tablespace instead of assigning these privileges to every user account.
Suppose you have an oracle user appdba. Grant DBA role to appdba and you can use this user to import data into any tablespace like this:
imp appdba/pwd file=fromuser=username touser=targetusername
exp appdba/pwd file=owner=username
where the owner is the username for which you want to export data