I've seen a few threads recently about handheld emulation, and both times it was focused on the original DS family. Emulation on those consoles is definitely much more well documented and cheaper, so if you're looking for ease or something low cost, it's a great option, but for anyone who wants the 3DS library or a bit more of a premium experience, I'd recommend springing for the 3DS.
I'll stop soapboxing about how great of a console it is and get to the main point: playing NHL on the console.
1. You will need a homebrewed console, preferably one of the "new" models for speed purposes. If you need to homebrew your 3DS, follow this guide here.
2. After you homebrew the console, I'd recommend installing RetroArch, which LibRetro outlines how to do in this YouTube video. This is important just to make sure any cores the game needs are on the console, since sometimes the .cia files (how the console reads games) function as forwarders to RetroArch instead of an independent app.
3. Rinse, and repeat Step 2 with the .cia of your choice, found right here.
NHL 94 (Genesis).cia NHL 94 (SNES).cia
For now, only the original games are on this thread. If you'd like to make your own injections of other ROMs, use this link for SNES, and this link for GENS.
If you have any questions, please let me know in the thread.