Characters are from PHIGHTING! (Roblox) and most of the audio sources are listed in the video!
For some specific credits:
K_K voiced by https://youtu.be/iyUQEg16Bpg
Hallownest Vocalized refers to the mod for Hollow Knight
Sans voiced by https://youtu.be/oERgRizceRs
Sword - 0:00
Skateboard - 0:12
Biograft - 0:25
Katana - 0:32
Banhammer - 0:37
Rocket - 0:45
Slingshot - 0:52
Hyperlaser - 1:02
Shuriken - 1:14
Medkit - 1:22
Boombox - 1:31
Subspace - 1:41
Vine Staff - 1:54
Darkheart - 2:08
Venomshank - 2:23
Firebrand - 2:34
Illumina - 2:46
Windforce - 2:58
Icedagger - 3:10
Ghostwalker - 3:17
Broker - 3:30
Zuka - 3:37
Dom - 3:47
Valk - 3:56
Lightblox - 4:05
Ghosdeeri - 4:23
Traffic - 4:29