如果需要所有组合，则需要执行完全联接，这取决于您的配置单元配置，您可能需要设置以下属性

set hive.mapred.mode=nonstrict

此查询适用于您的案例。演示：

create table tmp3 
(
id_1 string, score int, id_2 string, score_2 int

);

INSERT INTO TABLE tmp3
VALUES (77, 10,    88,   50),(77  ,  10   , 88  , 30),(77  ,  25  ,  88 ,  50),(77  ,  25  ,  88 ,  30);

select a.id_1, a.score, b.id_2,b.score_2 from 
(
select id_1, max(score) as score from tmp3 group by id_1
) a
full join 
(
select id_2, max(score_2) as score_2 from tmp3 group by id_2

) b;

结果

a.id_1,a.score,b.id_2,b.score_2
77,25,88,50

顺便说一句，根据您的数据大小和id的分布情况，fulljoin可能需要一些时间。。
更新：更新答案以使用窗口函数alllowing为最大分数选择多个列

select a.id_1, a.score, b.id_2,b.score_2 from 
(
select id_1, score from (
select id_1,  score , 
ROW_NUMBER() OVER (partition by id_1 order by score desc) AS row_num
from tmp3
) x1 where row_num = 1
) a
full join 
(
select id_2, score_2 from (
select id_2,  score_2  ,
ROW_NUMBER() OVER (partition by id_2 order by score_2 desc) AS row_num
from tmp3
) x2 where row_num = 1

) b;