Alright, i got a few ideas for when you finish. They use 2.0's features, so you might wanna write these down for later..
-Mario Kart Mode-
Item: Lightning Strike - Makes everyone infront of you smaller, then bigger. The person in first place grows last. When smaller, speed reduced, yadda yadda.
Item: Mega Mushroom - Makes you bigger for a while. Also makes you faster. (And maybe squish anyone in your path? Star-style or MarioKart-style (squash)?)
Item: Bullet Bill - ZOOM across the track, perhaps across Waypoints for a small amount of time. Enemies get hit, Star-Style.
Item: Seeker Shell - Oh, it's the all FAMOUS 1st place seeking shell! When used, the shell will follow higher-than-Bullet Bill waypoints until it found No. 1. Once it does, it drops and creates a bombsplosion! (The Seeker makes MarioKart, hated by all, it makes MarioKart what it is. It's like SRB2 Emeralds in Match. Hated by pros, but it makes SRB2 Match.)
Fixes:
NiGHTS - Make emblems and hoops respawn.
NiGHTS - Make rings restore Dash Power.
Just don't worry 'bout these. Jot 'em down, write 'em later.
EDIT: Whoops! Typed Emblems instead of Emeralds! Thanks for pointing that out.