i am surprised to hear you guys having trouble with diddy kong racing cause I beat the 64 version in about a day, got it on a rom a few years later and beat that in a few hours, and then the DS version in less. I really enjoyed the game and thought it had a medium-light amount of difficulty!
as for the game that frustrates me most: F-Zero GX.
It took me like a day to beat the first event race with Goroh, I think I beat the second one, but last I checked I was on the casino level and I have been for like a few years... fucking thing...
Just up and up beating DKR wasn't the troublesome part, though I seem to recall having some difficulty later on. It was the coin challenges that gave us such trouble. And if i rememebr correctly, and I might not, but you got balloons from the coin challenges that you would need later to open doors to more levels. Like, you got one balloon for just winning the race, but another for going back and getting all the coins AND winning the race. And there's be like 10 courses but the door to the next area required like 18 balloons so you HAD to finish 8 of those coin challenges.
that's what gave ME trouble anyway.