SQL> CREATE OR REPLACE type num_tab is table of number;
  2  /

Type created.

SQL> create or replace package pipeline as
  2    function get_num_row return num_tab pipelined;
  3  end;
  4  /

Package created.

SQL> create or replace package body pipeline as
  2  
  3  function get_num_row return num_tab PIPELINED is
  4  begin
  5  for i in 1 .. 5 loop
  6    pipe row ( i );
  7  end loop;
  8  return;
  9  end get_num_row;
 10  end;
 11  /

Package body created.

SQL> 
SQL> 
SQL> select * from table(pipeline.get_num_row);

COLUMN_VALUE
------------
           1
           2
           3
           4
           5

CREATE PROCEDURE curdemo()
BEGIN
  DECLARE done INT DEFAULT 0;
  DECLARE a CHAR(16);
  DECLARE b,c INT;
  DECLARE cur1 CURSOR FOR SELECT id,data FROM test.t1;
  DECLARE cur2 CURSOR FOR SELECT i FROM test.t2;
  DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET done = 1;

  OPEN cur1;
  OPEN cur2;

  REPEAT
    FETCH cur1 INTO a, b;
    FETCH cur2 INTO c;
    IF NOT done THEN
       IF b < c THEN
          INSERT INTO test.t3 VALUES (a,b);
       ELSE
          INSERT INTO test.t3 VALUES (a,c);
       END IF;
    END IF;
  UNTIL done END REPEAT;

  CLOSE cur1;
  CLOSE cur2;
END

1) use a refcursor as the return type
2) use an object table as the return type
3) use a mulit-delimited string as a return type (clob most likely)