How do you get to the top of mt Mortar?

Answer 1

It's dangerous to go alone, take this:

http://www.psypokes.com/hgss/gamemaps.php?map=mtmortar

Or, if you were asking about G/S/C:

http://pokemonelite2000.com/gsfindtyrogue.html

Don't forget a ton of max repels and a few escape ropes!