with t(grp_id, owner_id,start_date, end_date, act_type, type_code) as (
select 59,4231298, date '2018-09-26', date '2018-10-11','dev','OB' from dual union all
select 59,4231298, date '2018-10-27', date '2018-11-07','dev','OB' from dual union all
select 59,4231298, date '2018-09-30', date '2018-10-07','test','OB' from dual union all
select 59,4231298, date '2018-10-31', date '2018-11-03','test','OB' from dual union all
select 59,4231298, date '2018-10-31', date '2018-11-03','prod','OB' from dual union all
select 59,4231298, date '2018-09-30', date '2018-10-07','prod','OB' from dual 
),
x as (
      select  t.*,
              ceil(row_number() over(partition by grp_id,owner_id,type_code order by start_date) / 3) grp
        from  t
     )
select  grp_id,
        owner_id,
        type_code,
        dev_s dev_start,
        dev_e dev_end,
        test_s test_start,
        test_e test_end,
        prod_s prod_start,
        prod_e prod_end
  from  x
  pivot(
        min(start_date) s,
        max(end_date) e
        for act_type in ('dev' dev,'test' test,'prod' prod)
       )
/

    GRP_ID   OWNER_ID TY DEV_START  DEV_END    TEST_START TEST_END   PROD_START PROD_END
---------- ---------- -- ---------- ---------- ---------- ---------- ---------- ----------
        59    4231298 OB 10/27/2018 11/07/2018 10/31/2018 11/03/2018 10/31/2018 11/03/2018
        59    4231298 OB 09/26/2018 10/11/2018 09/30/2018 10/07/2018 09/30/2018 10/07/2018

SQL>