Question: Smash modding- Does Smash mods brick the Wii U and 3DS versions of Smash? Also, which skins/stages should i get?

Hello, everyone! It has been months since I last posted here. The reason is that my school district blocked me accuses to this wiki and could go in anymore. Plus, I had it rough all this year but now im back.... for a short time. While Im here I need to ask a question to everybody. Ive been interested to mod my 3DS version of smash and friend wanted to mod his Wii U version. However, his parents are too afraid that if we mod his Wii U, it will get "Viruses" and what not and will brick the console. Its because his dad is a tech-guy with his computer and since he knows so much of computers, he thinks that console functions are no different to a PC. I keep telling him it can't be bricked, but he needs solid proof to convince them. I too want to mod my 3ds version... but i don't know how to? Does anyone have any idea how to mod the 3DS? I kinda know how to do that for the Wii U but i only managed to Mod songs and that's it. Plus, is there any good Skins and Stages that you would recommend. No, Marth(Papyrus) or Ness(Mr.Karbs) skins. Some thing like Luigi(Mr. L) or just simple colors. Something that makes sense to the character. I only want non-meme costumes. Ill see you all in the next one! STAY FRESH!!!!!