How to add custom alert sounds to Gnome (Ubuntu 18.04)

I'm currently doing my yearly-ish reinstall of my OS. This time doing a fresh install of just basic Ubuntu with gnome, having previously used Ubuntu Mate for the past 1.5-ish years. I like to customize my OS slightly, to give it more personality. For this reinstall I decided to name my OS `mimikyu` after my favourite pokemon. Anyhow, during the process of tweaking I had the idea of making the alert/notification sound the "cry" of mimikyu. My Google-fu wasn't strong enough to able to find a solution online, but I eventually figured it out. Maybe this is of help to someone else in the future.