Iris has developed each time she appeared, from her debut to the Don Battle to the Donamite to the Ferroseed Research Center incident to the Junior Cup; something has changed in each of those instances. There's nothing stagnant about Georgia; she's one of the best written rivals in the whole anime, IMO.
How is that sad? That's development! Georgia is easing up on her petty grudge and finding a better calling in fighting a worthy opponent.which is sad since she clearly has more interest in beating Iris specifically than actually beating dragon-types, since a) she could beat Iris/Axew early on, b) she... could just go off and actually fight them.
Again, what? How has Burgundy "levelled out"?She hasn't levelled out like Burgundy has, and even she has a bit to go
Burgundy's the one stuck in a rut here: still C-class, still obsessed with beating Cilan, still losing to everyone.