select team1.name as firstname, team2.name as secondname 
from football_teams team1
join football_teams team2 on team2.id_age = team1.id_age
where team1.ID_AGE = 1
order by team1.NAME,team2.name

Команда1  Команда1
Команда1  Команда2
Команда1  Команда3
Команда2  Команда1
Команда2  Команда2
Команда2  Команда3
Команда3  Команда1
Команда3  Команда2
Команда3  Команда3

$age = 1;
$queryTeams = "select team1.name as firstname, team2.name as secondname 
	from football_teams team1
	join football_teams team2 on team2.id_age = team1.id_age
	where team1.ID_AGE = '$age' 
	order by team1.NAME,team2.name";
$resultTeams = mysql_query($queryTeams);
if(!$resultTeams) {
	exit(mysql_error());
}
$rowTeams = mysql_fetch_array($resultTeams,MYSQL_ASSOC);

foreach($rowTeams as $key => $value){
	echo $key.' '.$value;
}