It's your standard regional/match type championship setup. I'm thinking authority gained would go in this sort of hierarchy.

[Insert home nation/region] Champion holds more authority than that of a regular wrestler in a given region. Always has more authority than someone who has thus far never had a belt before. We may not get into this, because very few of our wrestlers are actually from the same place, and we mostly operate at the central arena anyway. 

International Champion has power over Regional champion, because it applies to all terrestrial regions.

Tag-Team Champions would beat out International, because it applies to the match type itself and not the regions of the planet. Therefore, they hold authority as some of the top match-type contenders in existence, not on the planet.

Hardcore Champion/Royal Rumble Champion beats out Tag-Team, because it's the same achievement but not split between people.

Bustermania Champion beats out all others, because it means you've beaten (Or, by proxy beaten) all the other wrestlers in the federation, in the same way that being the Arena Champion in Oblivion makes you responsible for thousands of deaths.