I know they exist in Mario Karts 7 and 8, but I rarely came across those. Very rarely would I have a session without seeing a hacker. A good room could easily be ruined because of Mr. Imagine having over 9,000 VR points and losing over 300 of it because you got disconnected despite having a good connection. Online stability was the worst the series has ever had. Because of this and because of overpowered wheelies, if you didn't use Daisy on Mach Bike or Funky Kong on Flame Runner, you had no chance. Bikes were overpowered because of wheelies. Getting 3 stars was incredibly painful due to all the bulls*** requirements and rubber-banding AI.
Why was that thing in 1 on 1 races? The items made the game horribly unbalanced. Blue shells up the ass, POW was useless, and don't get me started on the thunder cloud. Seriously, Funky Kong, Dry Bowser, and Baby Daisy? Some character inclusions were very questionable. It had some of the worst tracks ever, as well as some of the worst choices for retro tracks.