In musia's short history it has had a number of champions and in the hall of champions all of the past champions can be challenged, sometimes even other champions will show up too.
Former musia champions:
Astra meyga
Personality: she was the second champion of musia and was dethroned by deva, she is the youngest of the meyga's but she doesn't talk to her siblings very much, she seems very distant
Pokémon: chandelure, Mimikyu, aegislash, umbreon, gallade, and carracosta
Home region: kalos
Dream: accomplishedTetsuya striker
Personality: the first of musia's champions he was swiftly defeated by astra thanks to his mostly fighting type team
Team: infernape, loppuny, toxicroak, krookodile, blastoise, arbok
Home region: musia
Dream: accomplishedDeva ravenmore
Personality: most say that her defeat by the current champion was a fluke but she has made no move to try and reclaim her former glory, strangely many people still think she's the champion since the real champion doesn't show up much
Team: honchcrow, swanna, roserade, magmortar, electivire, smeargle
Dream: unknown
Home region: Kanto