One way to replace is to use s///:

use strict;
use warnings;

my $text;
while ( my $text = <DATA> ) {
    # match a word that contain 'ou' or #
    if ( $text =~ m/(ou)|(#)$/ ) {
        $text =~ s{[/\\]}{-}g;
        print $text;
    }
}

__DATA__
hello.world#
world\tour
Game.started
[download]

That replaces the \ and the / with -. You can add the rest.

• perltidy is nice.

UPDATE: added alternate delimiters in response to OP private msg.