you have to beat them 100 times
Yes, you receive a silver print for defeating them, which can be found in your vs. seeker. Beat the battle brain a second time and you receive a colored print.
No, the Battle Frontier can only be found in Emerald, Platinum and HeartGold/SoulSilver.
Battle 21 trainers without losing in a row and then you will face Palmer the frontier brain if you beat him you will get a silver print and if you beat him again you get a coloured print these are found on the vs recorder
No, Mew is found on faraway island and although several charicters mention mew on battle frontier you cant find it anywhere on the island
Sudowoodo can be found after you defeat the elite four. Sudowoodo is located at south-eastern area of the Battle Frontier.
There is a sudowoodo to the right of the battle palace near it is some water you can surf on go down and into the cave this is artisan cave the only Pokemon that is found here is smeargle other then that you can't find any other Pokemon in the frontier.
TM30 Shadow Ball is found on Route 210 or buy spending BP in the Battle Frontier shop.
i havent found it
Yes, you must give it a razor claw found in victory road or bought at the battle frontier and level the sneasel up at night.
TM40- Aerial Ace can be found in Mt Mortar. You can also buy this TM at the Battle Frontier for 40BP.
The Razor Fang can be found in Route 214 with the Dowsing Machine and in Route 225, too.
none i havent found any that have