Citadel

At the end of a Super-Duty Wormhole leading to the "Carina Dwarf Spheroidal Galaxy" sits the "Citadel."
A space station the size of Saturn
The area has been named the neutral sector and covers the whole of the Carina Galaxy.
No one faction is in control of that area. It is a place of trade and arbitration.
The embassies of many species or factions are represented in the Citadel.
It is unknown who built the Citadel, but it is thought to have been constructed by an elder civilization. The oldest parts of the station could be millions of years old, with the self-replicating technology constantly repairing and adding sections.

A Senate is based in the Citadel, with the job of arbitrating between species and factions.
Representatives from many species are in the station, including non-interstellar civilizations, especially those in disputed regions.
Even the Earth has an embassy on station.

The station draws power from many Dyson spheres, feeding a vast amount of energy to enforce or defend the galaxy.
Any species that doesn't like the result of an arbitration and trys to reverse a judgment by force, will soon start to regret that action.
The remains of destroyed hulks of ships that used to be war fleets are still drifting in the Carina Galaxy, showing the ones that have tried and failed.

Disputes can be settled in several ways. One way is through negotiation on the Senate floor, which involves continuing talks and finally hammering out a treaty.

The second is in the arena.
The vast arena area can accommodate many configurations, depending on the battle rules and type. It is ready to settle a dispute, champion vs. champion, not in a war but in a battle or matchup.
The arena has been configured for many forms of matches in its history.
It has seen wrestling matches, boxing, last-standing NHB fights, ultimate surrender fights, danger pits with traped walls, cage battles, and even duels with weapons. Depending on the rule book, matches can be lethal or ko/submit/pin.
The winner takes all the disputes settled.

Citadel is also the hub for the premier fighters to compete in Universes Combative Entertainment (UCE) matches. These matches are broadcast to every corner of the known universe and some unknown parts, too. Some past champions have gotten fame and fortune in every part of the universe through success in the arenas.

The arena also hosts a regular card of matches, attended by a passionate and large fanbase that packs the stands on match days.
There are many championships run and many belts to be battled for to wear as champions in the division and match tournaments.
In this, all arenas are non-lethal, but the range of battle types is as vast.
Inter-species and same-species matches are held. Tournaments range from a royal rumble to a stun handgun fight, a danger wall pit fight, a three-way pin wrestling match, a sex fight until one can't go on match up or a boxing match, and anything else you can think of all can happen in the Citadel arena.
Underground gambling on the outcome of fights is common. The Jeraptha have an almost frantic urge to gamble on any result of any matchup and usually run the gambling rings.

Members can be original characters or characters from TV, Games, Movies, Anime, pro wrestlers/fighters, or anything in between. All are welcome to test themselves.

The arena is used for disputes but is also busy holding a program of championship competitive matches to entertain and enjoy.
The Arena can be configured as a Wrestling or boxing ring, an urban battleground survival Arena, or another configuration you choose. Some suggestions are in the pictures section.
The choice is yours and your opponents, as are the rules.
Depending on the competition style, there are some Championship belts to compete for. If there's interest, tournaments can be organized.

Some noted matches in recent years were.
A three way cage fight last one standing bettwen.
Major Motoko Kusanagi (ghost in the shell)
Vs
EDI (Mass Effect 3)
Vs
Rommie (Andromeda)

Till one can't go on, ultimate surrender match.
Colonel Wilma Deering (Buck Rogers in the 25th Century)
Vs
Counselor Deanna Troi (Star Trek, TNG)

Battleground arena. Anything goes.
Bobbie Draper (The Expanse)
Vs
Chiana (Farscape)
Vs
Gamora (Guardians of the Galaxy)
Vs
B'Elanna Torres (Star Trek Voyager)