Code:
$Play SFX on Spike [UnclePunch]
C208DEC8 00000009 #Play SFX on Meteor Spike.asm
2C1C0003 40820038
807D1848 2C030122
4082002C 48000021
7C6802A6 80630000
3D80801C 618C53EC
7D8903A6 4E800421
4800000C 4E800021
CCCCCCCC 1C7C000C
60000000 00000000
With this code you'd replace "CCCCCCCC" with the SFX ID you want to use instead. This plays when hitting an airborne opponent with a spike, but it doesn't play at low percents. In addition to this, you can replace a global sound effect with Smash 4's meteor smash sound effect and you're done, although I think the sound is different depending on which sound effect you replace, not entirely sure why, I just know Melee adds tone shifts and all depending on the sound effect, it's odd.
Either way, I already did everything for you, but you're going to need to open up GameCube Rebuilder or Data Texture Wizard to replace an ssm file located in the US folder inside of the audio folder with this one:
https://cdn.discordapp.com/attachme...55391399017578525/smash4spikesfx-nr_title.ssm (As you can see, you replace a file called nr_title.ssm, hopefully it's nothing complicated.)
After you replace that file, edit the "CCCCCCCC" in the code with "00004E22" and now you just start using the code and you should hear it ingame when you spike someone. I replaced one of the announcer's unused voice lines, so you won't hear this sound effect anywhere else except during a spike.