The sixth badge is at the Fortree city gym.(The city full of trees). The gym is blocked by something so first continue your journey east of the the city to find Steven.He'll help you!
Then go back to fortree and use the item you got from Steven to clear a path!
Yes, on pearl you go to the palpark and you transver 6 Pokemon from Sapphire to the pearl game from the menu.
fortree city
In Fortree City.
Velistone City
Saffron city.
Saffron city.
Cinnibar island.
it is in the dotted hole on 6 islland
Beat the Gim Leader.
You'll get 6 Pokemon of the player's choice that were originally on the Pokemon Sapphire cartridge... but only if you choose to import them to Pal park.
On cinnabar island but you need to get the secret key in Pokemon mansion first.
Pokemon Ruby has Pokemon that Pokemon Sapphire does not and Pokemon Sapphire has Pokemon that Pokemon Ruby does not.