I was wanting to make a run in tears of the kingdom but i cant record the switch with my pc and idk how to put a timer while recording in mobile

You could just not add a timer. The mods will retime from the video anyway.

You're gonna need to buy a capture card most people use one from elgato.

A capture card would help, but it isn’t required. Pointing a camera at the screen is acceptable for most leaderboards.