$battlepokemon= array();

$i = 1;
while($rows = mysql_fetch_assoc($res))
{
$path = mysql_query(" SELECT * FROM pokemons WHERE pk_id = '".$rows['pkmn_id']."' ");
$pokemon = array(
'opponent_increment' => $i,
'id' => $rows['pkmn_id'],
'battle_poke'=> mysql_result($path,0,"path"),
'battle_level' => $rows['level'],
'battle_health' => $rows['health']
);
$i++;
$battlepokemon[]= $pokemon;
}

$i = 1;
foreach ($battlepokemon as $key => $value)
{
if($value['opponent_increment'] == $opponent_increment)
{
$value['battle_health'] = 0;
echo "Data replaced!";
}
$i++;
}
print_r($battlepokemon);