OMG Gyromite! You're right, this was the version of the Nintendo I got as a child. Of course, being an uncordinated 11 year old, I couldn't get R.O.B. to do what I wanted half the time, so I found the ambedexterity to operate both controlers at once (not using the feet, but both hands.) Of course, it was easier in Mode B, since you didn't have to worry about moving the professor, too, but I was still able to beat both. I can, however, recall how annoying it was when the damn professor got stuck and had to be "mercy-squished" or the board reset. My favorite tricks were bonking him on the head with the pillars (but not squishing him) and watching him bounce back up and trapping the Snicks rather than squishing them. That took some doing sometimes.
I also feel I should mention that the theme song to Gyromite remains one of my all-time favorites to this day. There were times where I would just leave the game on, not even playing it, so I could listen to that fantastic in-game tune play on an endless loop.
As a side note, my father HATED the music to this game because I, being an 11 year old, played the thing ad-infinitum until I'd beaten it (and then some) and he, unfortunately, was often home on sick leave and had to lie in bed listening to the music ad-infinitum. It was this and Tetris, I think, that made him encourage me to move my room up into the attic so he didn't have to hear it at all hours.