He will be on your way through stark mountain, then after looker arrested team galactic, he will be on the survival area forever, you can battle him on sundays and saturdays, he could visit your villa to on resort area(you need the national pokedex to get through survival area and resort area).
Survival area
After you beat him, continue on with the game. I think you run into Barry after you beat him, or it might be before..
Milotic
yes
you trade Pokemon XD gale of darkness(after beating the game) with Pokemon ruby, sapphire, leafgreen, or firered then if you have national dex on pearl diamond or platinum you can transfer the Pokemon from the gba game to platinum on the main menu
The first thing you have to be sure of is that you have beaten the Elite Four. Do that first!
Well, if you want to beat Pokemon platinum, you would have to go to a website that has walkthrough cheats...
After you beat him, continue on with the game. I think you run into Barry after you beat him, or it might be before..
Milotic
no there is not. I beat the game
you have to beat the Pokemon champion and later on in the game you will complete it
You can never trade Pokemon from Black to Platinum, because Generation V Pokemon do not appear in Platinum or any other game before Black and White. However, you an transfer Pokemon from Platinum to Black after you beat the game.
yes
Yes.
no but you must have the national dex on platinum
after you beat Pokemon ranger game enter a code in ranger mission and they will give you a manaphy egg then migrate it to your Pokemon platinum pearl or diamond game.
All you need to do is get all eight badges and defeat the Pokemon League. But, you can decide your goal to beat the game. You still have to beat the Pokemon League, but afterwards you can decide on your goal. Your goal could be to catch all Legendaries of that game. You goal could be to catch a number of Pokemon. But, the true way to beat the game is to beat the Pokemon League.
Your rival in Pokemon platinum is a spiky haired blonde boy originally called Pearl for the game but called Barry in the US/English anime and Jun in the Japanese anime.