Do I need to beat the IBM in ng+1?

As the title says. I was wanting to defeat the IBM in ng+1 just once so that I can have its goop to dupe going forward, but I read somewhere that it's actually easiest to defeat her in ng+4. I assumed it was easiest to beat in +1. Can anyone vouch for the +4 thing? Also, if I should beat her in +1, any advice on how to do so would be great. Much appreciated