I'm a bit confused here. You're telling me that Mariposa and the other princes been fighting people well above their power level without the Evil God's strength this whole time. Phoenix I get, but the rest? Kinnikuman power scaling is so wonky.
it's possible with B.I.S/KKD, since they temporarily boost their power levels, every chojin has access to it as long as they have regular feelings, also we've been known ever since the OG series that you can make up for the lack of power with technique, the Pheonix fight with Omegaman aristera even reiterated this point, but if your oponent also has as much technique as you, then you're screwed.
Also the princes are not pushovers, only aristera who was not only the leader of the centauri but also a mutant anomaly who could absorb other chojin's power levels had managed to force Pheonix to use his god powers, the fact that one of these 5 great times can also force mariposa to use it can only mean that they are strong asl too.