the original tag series stuff could be waved away since you know, no-one knew Terryman was in the Great costume at the time, and when everyone DID find out, they were already like half way through the final match.There don't seem to be any rules regarding that, considering they allowed Neptuneman to kick his partner off his team after he was defeated and replace him with one of the guys they were supposed to be fighting (with the justification "well, we allowed Terryman to take Kamehame's place in the last tournament, so why not?"). If anything, THAT should have been a rule violation of some sort.
although its a bit amusing actually that you brought up the whole Neptuneman/Mammothman shizznit (god knows I love talk about that clustereff) since Harabote only allowed it because he was feeling particularly dickish and explicitly stated the whole Terryman/Kin Great debacle as the reason why he was allowing the team up.
tl;dr Harabote is bipolar.