*We* can’t *go* ahead of me *on* MarioKart! I’m *a* number one racer!
It's very easy to understand what you mean, so it's really not bad! If I had to say it myself, I would say:
"You can't get ahead of me in Mario Kart! I'm the number one racer!"
Here, "you" is best because we often use it to mean "anyone". For example, if you talk online, or to a group of people: "You shouldn't have to work too much.", it will be understood that you are not talking to a single person like we would usually use "you", but instead, you are talking to everyone/anyone.