you cannot just 'PLUG-IN' the datafiles into another database.
in source :
1. make sure there is no other user;
2. do a clean restart.
3. backup the control file to trace;
4. shutdown
5. DONT OPEN THIS DATABASE UNTIL you are done with step cloning the database in another machine.
6. copy all the initsid.ora,datafiles, controlfiles
   logfiles,archived logs and evertyhing to the other  machine

in target machine:
1. install oracle
2. DONT CREATE A DATABASE.
3. edit the traced control file script to reuse the existing datafiles and control files.
make sure all the path locators are correct.
4. use this script to create the database.
5. now, when You create the database, it will use the existing control files and datafiles.
6. if everything is ok, open the source db.
else
startover again.
this is pain...
easiest way would be,
create the same tablespaces in another database ( like the target db).
create the same users.
export source.
import into target.