It seems that there have been some topics relating to the Adventure Mode story. I probably have something to consider...
Event 1
At some point in the story, Kirby ends up at a forest. He then runs into Yoshi, who is sleeping near a tree. Kirby then gets ambushed by Koopa Troopas and Kritters, and manages to briefly hold them off. The scuffle wakes up Yoshi, and he gives a helping hand to Kirby. The two then work together to traverse the forest.
Throughout the level, Yoshi and Kirby have to get past Kritters, Goombas, Koopa Troopas, and even the Hammer Bros..
Event 2
Halfway, a cinema will play where even more of the enemies stated above start to ambush Yoshi and Kirby. They eventually get overwhelmed by the ambush, but then, an airship comes falling down to the ground, knocking back a good portion of the enemies.
Yoshi and Kirby check out the airship, but then realize that they're still being ambushed. However, before they could do anything, someone (first appearing as a silhouette) jumps out of the ship and easily brushes aside the enemies. The camera then turns its attention to the character, who turns out to be the White Mage.
White Mage, Yoshi, and Kirby then spot Paratroopas and Neckys flying at them, but before they did anything, another entity appears to stop the assault. It was the Black Mage who stopped the flying foes. With the White Mage and Black Mage present, the enemies regroup. The cinema ends, and the player can then play as either Yoshi, Kirby, White Mage, or Black Mage.
The next portion of the forest level adds Neckys, Paratroopas, and Boomerang Bros., and there are some ambush areas as well.
Event 3
After getting past the extra enemies, Yoshi, Kirby, White Mage, and Black Mage run into a new threat, who is none other than King K. Rool. They have to confront and defeat the brute to continue on.
When King K. Rool is defeated, the four think they won, but soon learn that that K. Rool is a fake. Before they could react, someone attacks Black Mage and turns him into a trophy. The culprit is the real King K. Rool, and he orders his Kritter army to hold off Yoshi, Kirby, and White Mage. During that time, Bowser pops up to pick up K. Rool, and the evil duo escape with the Black Mage trophy. After repelling the Kritters, Yoshi, Kirby, and White Mage pursue Bowser and K. Rool. The level ends here.
Event 4
At this point, Yoshi, Kirby, and White Mage play a big role on the events that'll occur later on; they would be the only characters who don't get turned into trophies by Nightmare, who would be fully resurrected some time before that event.