Fennekin is the only Starter that has the Psychic Type in its Final Form, also Delphox gets Shadow Ball by Move Reminder.
Meowstic-M is pretty useful until a part of the game (Prankster Dual Screener)
Idk about Meowstic-F, but she's more like a Special Attacker than a Support.
Malamar is one of the best Psychic Physical Attackers in the game, I totally recommend.
Medicham too ^
Metagross is Metagross, you know.
Reuniclus is pretty bulky and some people say that he's the best Psychic type in the game, after the Trick Room I guess.
Can't confirm it for you, but you can try.
Well, I can only help you with this :v
I don't know so much about Ghost types but I think that Cofagrigus, Chandelure, Trevenant, Gourgeist, Mismagius and Dusknoir are pretty useful.
You can also change Rotom's form for better coverage, or is it against the rules? Since Rotom loses his Ghost typing after changing his form...