I bought Punch-Out from the Wii U e shop when they offered some classic NES titles for a few bucks a pop.
Sure, that was the version that replaced Mike Tyson with Mr. Dream, but I'm just gonna put this here anyway.

My precious memory from the NES version of Punch-Out was when I got stuck at King Hippo. My struggle caught the attention of my dad and my brothers who pitched in, in an attempt to help me figure out how I was supposed to get even a single clean hit in. Eventually beating him felt glorious, and it was a moment that made me fall in love with the series. I've never actually beaten Mike Tyson/Mr. Dream, but I'm sure that will happen some day.