CREATE TABLE table_204_335 (id NUMBER, "outcome" CLOB, "no." NUMBER, "date" NUMBER, "tournament" CLOB, "surface" CLOB, "partner" CLOB, "opponents in the final" CLOB, "score in the final" CLOB)

who did jim osborne partner with the most during the open era titles ?
SELECT "partner" FROM table_204_335 GROUP BY "partner" ORDER BY COUNT(*) DESC LIMIT 1
SELECT "partner" FROM "table_204_335" GROUP BY "partner" ORDER BY COUNT(*) DESC FETCH FIRST 1 ROWS ONLY