Most annoying character who stalks you

So in every race on MK8 Deluxe, I always wind up seeing Morton pass me. WITHOUT FAIL. EVERY. SINGLE. RACE. Curse you Morton! Anyone else have similar experiences? What characters?

Bowser, not only beating me in one of the several runs of attempting to get gold on Star Cup, but also making the worst tracks in MKPC - SNES Bowser's Castle. There is also Wario, who did the same.

Consider using a lightweight or middleweight character who excels in acceleration or handling to counter Morton's raw speed.
Learn how to consistently land mini-boosts from drifting to stay ahead on those straights.
Utilize items strategically. A well-timed red shell or lightning bolt can disrupt even the mightiest Morton.

are you talking about grand prix? because that is your rival every character has a one.

Thats what I initially wanted to post on SFA but I knew everyone was gonna facepalm me or something...

Cuz I think that rival theory might be very much true.
In Grand Prix, one of your characters are buffed up and will try to make you lose.
Sometimes it will be Bowser, other times, it will be Yoshi, other times, it will be Luigi. You basically have to play PERFECT in order to beat them. By PERFECT, I really mean PERFECT, cuz I always got a silver cup in Star Cup and couldn't be bothered to retry because I'd had to retry from the very beginning. Especially on tracks like SNES Bowser's Castle where its hard as shit to get first in Grand Prix, unless you are a online player with legitimate master or titan or something like that.