I love this pokemon's gothic looks. Because Male Kirlia have a male evolution a gen later, will male Gothorita get one, too? I bet it would look cool!
Anyways, Here's something that could work.
Nature: Bold or Modest
EVS: 252 HP, 63 Sp. Def, & 189 Def or 129 Sp. Def, 252 Sp. Def, & 129 Sp.Att/HP
Item: Light Clay or Lefties
Hidden Power Fire/thunderbolt/charge beam
It could help Gothitelle last some time. Best teamed up with a good steel counter.