from 8.0.5.2 you cannot do a direct upgrade to 9i.
you have to goto 8.0.6 or 8i.
easiest is to go 8i and then to 9i.
as migration from 8.0.5.2 is concerned,
i am almost doing it in a weekly basis.!!(to create 8i database COPIES in different machines for different purposes of application (lawson suite) upgrade.
You can choose any method u want (exp/import etc)
THE WAY I DO IT IS
1. copy and recreate the 8.0.5.2 in a new machine   (test Machine).
   do an OS cold copy of oracle software binaries
   AND database.
2. in TEST bring the instance up
   test whether this CLONE is working properly.
3. install 8i in a new home.
4. DONT CREATE THE SEED DATABASE.
5. use ODMA (oracle datamigration assistent) to migrate 8.0.5.2 to 8i.
6. before migration make sure you have added 30% more space in system tablespace in 8.0.5 databases.
7. the listener entries are automatically relocated 
   ( it will ask for your option).
   its upto u, to choose it.(i never do that).
8. bring the 8i instance up, check for any ISSUES.
   client connectivity etc.
   look for INVALID OBJECTS(if any) and recompile them.
9. do a migration for 9i.
10. READ the migration manuals . IT WILL GIVE U a lot of  information.
[b] 8.0.5 to 8i is not that complicated AS IT SEEMS IN ABOVE STEPS.[/b]