Hi! I recently bought a GameShark v3.3 from a garage sale and was wondering if there were any codes that would make practicing Mario easier and more efficient. Thanks!

There is a GameShark section in this guide that has links to a few GameShark resources, including a list of codes. I don't know how updated/accurate it is. You might also want to ask in the Usamune or even the main SM64 speedrunning discord.

https://docs.google.com/document/d/1TQ9MFbdSRZX_W329Vz72Ddbrr-EoW26dHdglNMzZTrs/edit