Pertaining to the base stats of the kaiju, a Japanese source suggests Kaiser Ghidorah was officially ranked as the most powerful monster in the Ghidorah family to date. This would mean that Kaiser Ghidorah is stronger than many Heisei series kaiju.
It is positioned as the highest-ranking monster of the Giddula tribe, and has a form resembling King Ghidora [46]
https://ja.wikipedia.org/wiki/Òé¡Òâ│Òé░Òé«ÒâëÒâ®
https://translate.google.com/transl...%82%B0%E3%82%AE%E3%83%89%E3%83%A9&prev=search
Kaiser born monsters are also portrayed in the movie itself to be exceedingly powerful compared to the rest, a super saiyan of sorts:
80
01:33:01,000 --> 01:33:05,200
You're an exception. Your power
hasn't been developed enough. 81
01:33:05,700 --> 01:33:06,800
What? 82
01:33:07,500 --> 01:33:09,500
You're a Kaiser. 83
01:33:10,500 --> 01:33:14,200
A Mutant that is half earthling half X-ian. 84
01:33:14,300 --> 01:33:18,400
The odds of such a creature
being born are on in thousands. 85
01:33:21,200 --> 01:33:23,900
You and I have one thing is common... 86
01:33:26,500 --> 01:33:27,900
We're both Kaisers. 87
01:33:29,900 --> 01:33:36,800
You have the ability to surpass
both human and X-ian. 88
01:34:11,100 --> 01:34:12,600
Ozaki! 89
01:34:13,600 --> 01:34:15,900
Wake up, Kaiser!
Kaiju to be considered:
-King Ghidorah (Showa, Heisei, Millenium)
-Mecha King Ghidorah
-Death Ghidorah
-Grand King Ghidorah