easiest answer to avoid getting banned, abide by nintendo T&Cs, do not run exploits to pirate games.
end of the day, you didnt buy the game (please folks dont give us that BS that you buy your games..... y'all can sing that song as much as you like, doesnt change the fact you are pirating) and play on an un modified console.
end of the day, the console and its software is nintendo's product, you only own rights to use it as set out in its T&Cs, if you modify or alter this then you are not running nintendos software, thus are not supported, so features such as online gaming runs the risk of being banned.
mainly because people who have modified consoles that allow piracy also allow other exploits such as cheats, so what gives anyone the right to firstly pirate a game and demand full access to its features when youve not paid for the product, but there are people who then think its ok to cheat online.
what gives people the right to not buy a game and cheat, thus ruining the gaming experience for those that have paid for the game.
if you "choose" to pirate, then you "choose" to accept that features such as online access runs the risk of being banned and to avoid doing it, if you want this feature then be like everyone else and pay for your shizzle.