Majuub

Rildo: So, you weren't using your full power, that I knew.

He said that just after Goku turned SSJ, he knew Goku was way stronger than he showed, when Rildo powered up, Goku was impressed but not suprised meaning he knew what was Rildo's power. He doesn't mean base Rildo is stronger than Chibi Buu, he was refering to full power Rildo. That one not as strong as Chibi Buu, he wasn't refering to base Rildo for sure since he was kicking him easily at base form so why would he be impressed by a being he can beat when he's not even transformed. He was impressed because he knew in order to beat Rildo he had to turn SSJ, so if meta Rildo is a little stronger than SSJ Goku and Chibi Buu is a little stronger than meta Rildo, we got our answer.

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