Water Stone- Castelia City (Answer Panpour), Driftveil City, Wellspring Cave (Dustcloud), Chargestone Cave (Dustcloud), Mistralton Cave (Dustcloud), Twist Mountain (Dustcloud), Challenger's Cave (Dustcloud), Victory Road (Dustcloud), Giant Chasm (Dustcloud)
Leaf Stone- Route 6 (Show all forms of Deerling in Season Institute), Castelia City (Answer Pansage), Wellspring Cave (Dustcloud), Chargestone Cave (Dustcloud), Mistralton Cave (Dustcloud), Twist Mountain (Dustcloud), Challenger's Cave (Dustcloud), Victory Road (Dustcloud), Giant Chasm (Dustcloud)
Fire Stone- Castelia City (Answer Pansear), Desert Resort, Wellspring Cave (Dustcloud), Chargestone Cave (Dustcloud), Mistralton Cave (Dustcloud), Twist Mountain (Dustcloud), Challenger's Cave (Dustcloud), Victory Road (Dustcloud), Giant Chasm (Dustcloud)
Thunder Stone- Route 9, Chargestone Cave, Wellspring Cave (Dustcloud), Chargestone Cave (Dustcloud), Mistralton Cave (Dustcloud), Twist Mountain (Dustcloud), Challenger's Cave (Dustcloud), Victory Road (Dustcloud), Giant Chasm (Dustcloud)
Moon Stone- Pinwheel Forest (From Lenora), Twist Mountain, Wellspring Cave (Dustcloud), Chargestone Cave (Dustcloud), Mistralton Cave (Dustcloud), Twist Mountain (Dustcloud), Challenger's Cave (Dustcloud), Victory Road (Dustcloud), Giant Chasm (Dustcloud)
Sun Stone- Relic Castle, Nimbasa City
Shiny Stone- Route 6, Dragonspiral Tower, Wellspring Cave (Dustcloud), Chargestone Cave (Dustcloud), Mistralton Cave (Dustcloud), Twist Mountain (Dustcloud), Challenger's Cave (Dustcloud), Victory Road (Dustcloud), Giant Chasm (Dustcloud)
Dusk Stone- Route 10, Mistralton Cave, Wellspring Cave (Dustcloud), Chargestone Cave (Dustcloud), Mistralton Cave (Dustcloud), Twist Mountain (Dustcloud), Challenger's Cave (Dustcloud), Victory Road (Dustcloud), Giant Chasm (Dustcloud)
Dawn Stone- Route 10, Wellspring Cave (Dustcloud), Chargestone Cave (Dustcloud), Mistralton Cave (Dustcloud), Twist Mountain (Dustcloud), Challenger's Cave (Dustcloud), Victory Road (Dustcloud), Giant Chasm (Dustcloud)
My source was Serebii and Bulbapedia
I know it's long but hope this helps =P