1) Must have good experience at SQL (e.g. joins, functions, sub queries, Data Manipulation etc).
2) Very Strong Oracle PLSQL programming experience (e.g. Procedures, packages, functions, exceptions etc.) in Oracle 11g or above.
3) Must have thorough understanding, knowledge, exposure to advanced PL/SQL (collections, Native Dynamic SQL etc)
4) Experience at Oracle performance tuning - Should be able to analyze execution plans, TKPROF and AWR reports.