It's been a long time since Ive played this game, but I know that there's a lot that it can be improved in this great video:
First, on
Spring Breeze, the 2nd Boss fight (lololo & lalala) you can get the
Crash ability on a room before, which kills the bosses ASAP, dunno if creating a parter & then getting back the
Cut ability is slower, but I doubt it.
Then, on the
Gourmet Race IIRC, you can skip it & it doesn't matter because you're not aiming for the 100% of the game. Now even if you want to pass it, you can cut some seconds in each track, here are some snaps of my records (though they are not played on the Grand Prix...):
As you can see, wing power can give you a better time by a considerable margin...
Next, on
Dinablade, IIRC getting the candy speeds you up & in the video he doesn't grab it, in the scene where you fight Chef Kawasaki, on the 1st stage; also IIRC if you grab the
Crash ability you can kill him faster, but it may slow you down when you create a parter, (have to check if it helps or not). Then on the 2nd stage, you can get the all mighty
Wheelie Rider, the most powerful permanent power BUT you need to play with 2 players in order to shoot those powerful stars, this will save you lots of time on further bosses, even on Dinablade...
Now, on
The Revenge of Metanight, when you fight the 2 Whispy Woods at the same time, I think that you can also cut some time if you use the ability that rise kirby with the Yo-Yo (forgot how's it called), because you can hit both trees at the same time... Then on the stage that he can get the Wheel ability, he can use again the
Wheelie Rider ability to kill ASAP further bosses, even the fight with Metanight can be cutted by a huge time...
At
The Great Cave Offensive everything is great, I really liked it.
And at the
Milky Way Wishes, since it takes to long to get the
Wheel ability, maybe you could "cheat" & play Halfmoon to get it free on the Computer Virus fight but after you passed Floria & got
Cut ability as is on the video, also it might help if you get the
Hammer ability on Carvos planet to kill bosses faster. Aside from that, I also think that everything here is great.
You don't need to record the ending after Milky Way wishes one, you could then reset the game & it gets saved... Also it would be great to include the Arena...
So, in resume, you can improve quite of time if you play with 2 players & skip the Gourmet Race...