https://www.eurogamer.net/articles/2017-06-02-mario-kart-8-guide-tips-tricks-shortcuts-deluxe?page=3
The link above will show the weight classes of all the characters
In today’s post I’ll be discussing the importance of weight classes. First off, your probably wondering what at weight classes. Well, simple. All characters in the Mario kart series are organized in weight classes, and their weight affects their kart stats (speed, acceleration, drift, handling, etc.). Knowing your character stats are vital, especially in Mario kart 8 deluxe since you can choose from three separate kart parts, each having their own stats. Your characters weight will raise come stats and lower others, that’s why it’s important. The stats for kart parts you should worry about the most is acceleration, traction, drift, weight, and handling. Acceleration is how fast your kart gets to top speed, meaning for fast recoveries and comebacks high acceleration is a must. Traction is how well your tires grip the road, and with low traction you won’t be able to drift sharp enough to take some turns. Drift is determined by all the stats combined, and drift is a very vital skill in the Mario kart series. You want a high drift, that way you can maximize the speed of your turns and take the corner as fast as possible. Weight affects how hard you are to push around by opponents, meaning a high weight means less chance of being pushed off road. However, it will lower other stats like acceloration and speed. As you can see, stats are very important, so keeping track of them while picking your character is key to becoming a true competitive mk player!