WITH T AS (
    SELECT 'AAA' AS v1, 'KAO' AS v2 FROM DUAL
    UNION ALL SELECT 'AAA', 'KBO' FROM DUAL
    UNION ALL SELECT 'AAA', 'KAO' FROM DUAL
    UNION ALL SELECT 'BBB', 'KBO' FROM DUAL
    UNION ALL SELECT 'CCC', 'KAT' FROM DUAL
)
SELECT v1, v2 FROM (
    SELECT
        T.*,
        CASE
            WHEN (
                COUNT(*) OVER(PARTITION BY v1) = SUM(DECODE(SUBSTR(v2, 1, 2), 'KA', 1, 0)) OVER(PARTITION BY v1)
            )
            THEN 'true'
            ELSE 'false'
        END AS only_ka
    FROM
        T
) WHERE
    only_ka = 'true'

WITH T (COL1 , COL2 )AS (
    SELECT 'AAA', 'KAOITD' FROM DUAL UNION ALL 
    SELECT 'AAA', 'KAIDJA' FROM DUAL UNION ALL 
    SELECT 'AAA', 'KBWSAZ' FROM DUAL UNION ALL 
    SELECT 'AAA', 'KBRWAD' FROM DUAL UNION ALL 
    SELECT 'BBB', 'KAOITD' FROM DUAL UNION ALL 
    SELECT 'BBB', 'KAIDJA' FROM DUAL UNION ALL 
    SELECT 'BBB', 'KBWSAZ' FROM DUAL UNION ALL 
    SELECT 'BBB', 'KBRWAD' FROM DUAL UNION ALL 
    SELECT 'CCC', 'KAOITD' FROM DUAL UNION ALL 
    SELECT 'CCC', 'KAIDJA' FROM DUAL 
    
)

SELECT COL1
     , COL2
  FROM T 
 WHERE COL1 = 'CCC'
   AND REGEXP_LIKE ( COL2 , '^KA' )