So I am new to the whole speedrunning thing and I was planning on a Super Mario Bros. run but I don't have a NES USB controller but I DO have just some random controller I got for my birthday so is using a NES controller required or can I use said random controller?

I don't think the controller matters, so long as you can't press left+right at the same time

Basically the rule of thumb is: as long as you're not using or doing something that you can't do on console you're fine.

Whatever controller you have should be fine as long as you're not trying to use some turbo functions or L+R simultaneously.

OK! thanks!