Use the self join with a condition so that a country cannot play against itself:

CREATE TABLE counties (
    name varchar(50)
);

INSERT INTO counties (name)
VALUES ('India'), ('Pakistan'), ('Australia'), ('Srilanka');

SELECT
     CONCAT(c1.name, ' vs ', c2.name) AS matchup
FROM counties c1
JOIN counties c2 ON c1.name < c2.name
ORDER BY
    matchup;

fiddle

More combinations can be achieved with <> in the condition:

SELECT
     CONCAT(c1.name, ' vs ', c2.name) AS matchup
FROM counties c1
JOIN counties c2 ON c1.name <> c2.name
ORDER BY
    matchup;

fiddle

I would suggest adding another column id to your table so you can get the correct result, for example:

CREATE TABLE country (
  id INT PRIMARY KEY,
  name VARCHAR(50)
);

and your query can be:

SELECT t1.name + ' vs ' + t2.name AS result
FROM country t1
JOIN country t2 ON t1.id < t2.id;

Result

India vs Pakistan
India vs Australia
India vs Srilanka
Pakistan vs Australia
Pakistan vs Srilanka
Australia vs Srilanka

Full example here

You can use CROSS JOIN , and WHERE c1.name < c2.name :

SELECT CONCAT(c1.name, ' vs ', c2.name) AS Combination
FROM counties c1
CROSS JOIN counties c2
WHERE c1.name < c2.name
ORDER BY Combination

Demo here