First you start from Solaceon, if you already got the SecretPotion from Cynthia you need to use it on the psyduck blocking the path (Route 213 i believe) and then just go through where the psyduck are and just keep going
She is in Celestic town. Fight the Galactic Grunt protecting the ruins in Celestic Town and Cynthia's grandmother will appear.
There are two choices: by snowpoint city by celestic town
Celestic Town, after you beat the Gym Leader.
in celestic town route 211
defeat the galactic grunt and give the mail to the Pokemon champions mother
nothing
There are two places to get it. Snowpoint city Celestic town
cynthia's grandmother in celestic town will give it to you after you beath the galatic boss and talk to the circle in the celestic cave...
one in celestic town sells full restores for 3000
you have to go through mt coronet from celestic town.
you go to the right of celestic town and use the poke radar
you go up through mont courent from celestic town