CREATE TABLE table_21434618_1 (team__number2 VARCHAR2, team__number1 VARCHAR2)

which team#2 played against poseidon neoi porroi
SELECT team__number2 FROM table_21434618_1 WHERE team__number1 = "Poseidon Neoi Porroi"
SELECT "team__number2" FROM "table_21434618_1" WHERE "Poseidon Neoi Porroi" = "team__number1"