I'm not as samrt as Plagueis, but I'll try: He could hide on a world with a culture far different from the galactic standard and control his operations from there. Let's say, for example, Voss. If he is enough of a threat, G0-T0 would turn his attention there. But most of his power base are droids and won't be able to adapt to the culture. And they also can't simply ignore them or blast their way through them. And everyone else G0-T0 sends won't be a match for Plagueis.
If that isn't allowed, Plagueis could develop a new culture, a completely new code of honor and combat rituals for his Sun Guard. Something G0-T0 is not familiar with. For example, let the command shift after 15 minutes of battle. Order them to take droids prisoners. Let them attack primarily low priority targets. All in all this might wear down his powerbase. (I would need much more time to develop completely new but still decently effective strategies, I hope you see the genereal idea, though.)
So basically Plagueis could adapt his strategy to target droids. Weapons, tactics etc. This would certainly make him more prepared. But the HK-50 droids are likely to be a spinball - and he won't see them coming. And remember G0-T0 is an Exchange boss, so his underlings are mainly organic.