Route summary
The main difference between Any% and Best Ending / 100% are the Rainbow Drops. Each world has one Rainbow Drop and collecting all 7 and defeating King DeDeDe at the end will unlock the game's real final boss, Dark Matter. 100% involves doing the Best Ending route while also completing all 6 Bonus Games found in Worlds 1 through 6, as well as collecting one Gooey Girl throughout the run.
Best Ending Route Overview
(_____) indicates what Animal Friend and/or Ability you should have entering a level.
1-1
1-2
Grab fire at start of level.
Midboss - Efreeti
You can use your Fire ability star to KO the boss and re-inhale it for Fire.
Ignore Rick from Animal Bag.
Grab Parasol at end of 3rd room.
1-3 (Parasol)
Use Parasol to break blocks for Rainbow Drop 1 in 3rd room.
Whispy Woods (Parasol)
Use Parasol to damage Whispy if apples don't spawn, otherwise use Parasol ability star as an attack.
2-1
Grab Coo from Animal Bag in 2nd room.
2-2 (Coo)
Grab Needle from enemy in 2nd room.
After completing 2-2 and after unlocking 2-3, re-enter 2-2.
Fly downwards to the bottom-left corner of the 1st room, enter door.
Use Coo + Needle to break blocks, grab Rainbow Drop 2.
Exit 2-2.
2-3 (Coo)
Grab Cutter on the door at the end of the 1st room.
Midboss - Jumper Shoot
Nruff & Nelly (Coo + Cutter)
3-1 (Coo + Cutter)
Grab Coo and ability at the end of the 1st room and inhale Stone.
Alternate route - keep Coo (Stone optional) through 3-1 and into 3-2 until you get Kine.
3-2 (Stone)
Enter the 1st door in the 2nd room.
Midboss - Master Green
Grab Kine from Animal Bag.
Finish level with Kine + Stone, or use Kine + Spark.
3-3 (Kine + Stone/Spark)
If using Kine + Spark, grab Stone at the end of the 2nd room and backtrack to the 1st door.
Go into the 1st door and then into the hidden door on the right in the dark room.
Use Kine + Stone to get Rainbow Drop 3.
Finish level with Kine + Stone.
Sweet Stuff (Kine + Stone)
4-1 (Kine + Stone)
Discard Kine and Stone before entering 4-1.
Grab Fire in the 1st room.
Midboss - Blocky
4-2 (Fire)
In the 1st room, use a precise jump to enter the 1st door and skip the 2nd door.
If you miss the door, you can use Fire as a back-up to re-enter.
If you do not have Fire, either reset the level or enter the 2nd room to fight Jumpershoot and grab Coo.
Keep Fire through the icicle room to skip having to re-grab in the Ice Block room.
If you lose Fire, enter the door in the Ice Block room to grab Fire.
4-3 (Fire)
Midboss - Mr. Frosty
Use Fire ability star to KO Frosty, make sure to inhale Frosty after the fight.
Grab Kine from Animal Bag, you should now have Kine + Ice.
At the end of the 4th room before the Goal door, drop Ice and inhale Fire.
4-4 (Kine + Fire)
Midboss - Efreeti
Recycle Fire to inhale the blocks underwater in the 3rd room.
If you lose Fire, you will have to reset the level.
Enter the door and use Kine + Fire to melt the Ice Blocks and get Rainbow Drop 4.
Finish the level with Kine + Fire, do not drop either.
Ice Dragon (Kine + Fire)
5-1 (Kine + Fire)
After Ice Dragon and before entering 5-1, drop Fire and Kine, then re-inhale Fire as Kirby.
Enter 5-1 with Kirby + Fire.
5-2 (Fire)
Midboss - Waiu
Grab Cutter after beating Waiu then finish the level with Cutter.