>>713818613
Golden Mushrooms are pretty low-tier when it comes to lightweight specials, since they're essentially 5 consecutive mushrooms in a game where no shortcuts warrant that many uses and snaking is already a dominant way of racking up speed. The Koopas are better since you typically gain access to triple reds in second and below for offense, and triple greens in first and other high positions both for defense and offense. Jr.'s alright, too. Diddy would be the best for frontrunning due to the giant banana's utility for trapping, and while it does work as intended in multiplayer, he's worthless in single player since the AI phases through stationary items. Babies are horrible.
As for why the Barrel Train is undeniably the most broken kart, it has the 2nd fastest top speed, average acceleration and good offroad (when most speed-based karts completely tank both stats), decent weight to be able to bump middleweights, the smallest hitbox, and notably, the way the kart is built allows it to work with DD's physics since it bounces around the least offering the most stability, a rear-tires-first turning style that plays into snaking perfectly (combined with lights having the longest drift miniturbo time). No other kart in the game can compare at all, but it doesn't get talked about as much as Dry Bones Dry Bomber, Funky Flame, Metal Mario Red Monsters and Yoshi Inkstriker due to the game being completely offline.