Some ninjas seem more powerful than they are because only players 200k-600k power higher than you have them. But most of them are just fast acting, and not really OP. When they were released for example, Hiruzen Edo, Naruto Ronin, Madara 5 Kage, Madara GNW.... IMO right now the only solo ninja that lives up to the hype are Grudge Kakuzu BT, Kushina BT, Naruto 6 Paths, and maybe Minato Edo BT+barrier. Yes they can be beaten, but for an average player those ninjas will give you a sizable advantage against another player that doesn't have them. Finishing Grudge BT moved me up ~100 spaces in Spacetime letting me qualify for the first time ever (barely) a few weeks ago. And with him I can often beat others 50-75k power higher than me (I'm just short of 300k power).