Oracle strong ref cursor with dynamic sql
There are probably better ways to achieve your underlying goal, but if you really want values from dynamic SQL into a strongly typed refcursor I guess you could do something like this:

create table TESTTABLE(TESTID number not null);
create global temporary table TEMPTESTTABEL(TESTID number not null);

create or replace procedure testprocedure is 
  type testtablerefcursor is ref cursor return TESTTABLE%rowtype;
  type testtabletable is table of TESTTABLE%rowtype;
  mycursor testtablerefcursor;
  mysyscursor SYS_REFCURSOR;
  mytesttable testtabletable;
begin
  open mysyscursor for 'select * from TESTTABLE';
  fetch mysyscursor bulk collect into mytesttable;
  close mysyscursor;
  forall i in mytesttable.first..mytesttable.last
   insert into TEMPTESTTABEL values mytesttable(i);
  open mycursor for select testid from TEMPTESTTABEL;
end;
/