Welcome back to the forums then Captain. Awesome nicknames by the way for the ones you nicknamed yourself.
Anyways, Aya's current filed is the Wasteland field which can boost moves that she is likely to use such as Sludge Wave (which you'll receive by beating her) and nerfing moves that would do Super-Effective damage to her such as Earthquake, Bulldoze, and Magnitude. That being said, you would want to try to use mainly Psychic types, but Ground types can still do some work still :] Other than your Donphan, which is relatively slow, you won't be doing as much Super-Effective damage to her so you may consider reworking your team for this gym.
Mons I would recommend to use would be Gothitelle, Meowstic, Malamar, Graveler, Piloswine, Dugtrio, Seismitoad, Marowak, Whiscash, and Gastrodon. If you need to find out where/what time to find these mons, check these two threads -> Pokemon Location Guide V2 and Reborn EV Training Guide.
Also, if you wanted to know what Aya's team was it is Nidoqueen, Tentacruel, Venusaur, Gengar, Dragalge, and Drapion.