ive been kinda wondering this, but does it matter which character you choose? i see people always playing as beartank but i cant really feel a difference between him and nyami, whos the character i usually use

You can use any character you want, but beartank is by far the best choice. If you try both characters in Time Attack and look at your speedometer, you will see that beartank is definetly much faster than Nyami.

Yeah beartank is overpowered. However for the New Game category, when beartank isn't available, I'm not sure if the other characters matter. I think they have slightly differing stats