Physical copies of the games. If they're e-shop exclusive, there is no retail cartridge of the game.
A header is a code that every retail cartridge has that is used to identify the game when going online. If Nintendo sees a single header online across multiple 3DS' (A public header), that 3DS will be temp banned.
To get a private header, you'd need a 3DS on 9.2 or lower > Rip a retail cartridge to .3ds format > Extract the header from that rom.
Buy a private header from someone trusted online (can be risky), which usually costs about $10.
Buy a PowerSaves Adapter and use that to extract the header from the save file (You'll have to lookup the guide on how to do this) - About $20 + a retail cartridge.
If those games came out as a physical cartridge & none of them came out recently, then yes.
Go to Sky3ds.com and follow their tutorial for setting your Sky3ds up, that or look up Sky3ds tutorials on this site.