You can't use the leak.The leak has version 0 so that is why I'm assuming you have the leak installed.You eather need the cartridge copy of the game or the eshop/freeshop version of the game(version 32 for sun and 16 for moon) to go online.You also have to make shure that the copy of the game got released for your region,you can easily do this by going to the eshop and checking if the game is available to buy (delete the leaks software and ticket first though before entering the eshop to decrease your chance of getting banned)
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It's best not to risk that.The leak comes from 4chan and is a reviewer copy so it's very likely it's rigged from going online.There is also a bug on it where if you enter the eshop and go to. The sun and moon section it asks you to update which isn't actually the update.