SQL Server 2005 Whole-Migration, which databases should I recreate?
If you really care to know which databases are in use, you have to use dmv's (log that data to a table as they get flushed out when server is restarted) or profiler (server side trace) and just filter out the logins and program names connecting to those databases.

once you have that info for your complete business cycle, you will be able to figure out what databases needs to be moved to new server.

also, backup/restore should be a preferred method unless you have a reason of not doing it.

note: we do not know your environment, nor your business so we CANNOT answer what databases you need to move.

reportserver* are eelayed to reporting server that might be installed on the current server.