This is by far one of my favorite moments in KH3 along with Kingdom Hearts in general for a number of reasons:
Sora walks towards Xeahanort by himself only for Goofy and Donald's feet to appear in the frame.
Sora realizes that Goofy and Donald are joining him to fight Xehanort.
Donald telling Sora that he can't forget about them with Goofy ruining Donald's line due to being his logical self tells by pointing out how they won't be able to do much without keyblades. I love how annoyed Donald is by Goofy pointing that out.
Sora, Donald, and Goofy place their hands in the middle as Sora says "Three half-pints together again"
Just, ugh! I love this moment so much!