Well each category has a rules on where to start and where to end the timer so onto the big topic: There's not much of a difference between emulator, arcade or VC in PS4 due to the games being pretty stable themselves. For attempts: It's up to you as long as you don't steal someone's else time and yes Time counter is needed to verify properly the run.

Perhaps if more people were running this game and could give an actual input on how differently the system works for each run it'd be debatable, but as for now the amount of people with a Sega saturn - PS1 - Xbox One (w Neo Geo) are like minimal, and we don't really know if there's a huge difference between an emulated arcade, a VC and a console, it'll be kind of a hassle.