If you have a modded Wii (Google if if you don't know what it means) You can download a homebrew called Mii Extractor. You can then open up your Miis from your SD card with Mii Avatar Editor and Change the Mii Avatar ID to: 00-00-00-00. This will give your Mii gold trousers. Then save it and use Mii Installer to copy the Mii back onto your Wii.
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If you mean how do you get them onto your 3DS through Streetpass, often the employees at the Nintendo store will have them (you might have to ask to street pass with them, because their devices get full), and you can also get them if you go to a place that can collect/distribute them for celebrations. Places like this are often games stores like GameStop, restaurants like McDonald's, and sometimes airports.
they are special miis that you can only get by scanning QR codes of them, for example there are new resident evil miis with gold pants, you can find it on google.
Special Miis are released from time to time and propagate across from person to person over streetpass.
to get a golden mii you have to svan a qr code or get them through streetpass
Miis with blue pants are miis that do not belong to you. You get these miis from the CHECK MII OUT CHANNEL which you can only get if you have WI-FI!
I'm pretty sure all Miis have navy blue pants. Unless you mark them "favorite" which makes their pants red/ The way you see Miis with blue pants is because if you go on Mii Contest Channel, and you go on posting plaza, you see other people's Miis, and because they are other people's Miis they have blue pants. (You can't edit Miis with blue pants)
100. This counts all Miis you make and all Miis you receive or download. (i.e. QR Code Miis)
they can watch youtube miis get killed
all miis are looking left to right and the odd miis are looking right to left in some cases they are walking left right and the odd miis are walking right left
Systems not transfer miis: DS Lite,DsiXL, and the origanal DS Systems transfer miis:3Ds and the Dsi (The Dsi may transfer miis...)
Not possible
you can have unlimited miis in your parade
No, there is no way to do so. The 3DS will support Miis, though.
umm no miis are only on the wii Mario kart
The Nintendo DS lite does not support and cannot download Miis.