I am new here and I need to know 2 things

1. if I speed run Mario bros or any new game can I do it on the switch online
2. How do you guys have the speedrun timer on runs

For the first question: https://www.speedrun.com/speedrunning/thread/6tgel For the second question, you don't need to worry too much about timers. They're really just for your benefit, except in rare edge cases where they're required to be on screen. I'm not sure exactly what you're asking though, so if you'd rephrase your question I can answer it more properly.

For the second question, you'll want to be using the program LiveSplit. This is a timer which you can manually control, although this is almost always only for the runner's benefit and not for moderators. You can use a window capture in OBS Studio to place it wherever you want in your video as you record.