Ooh ok I’ll do this with the Mahou Celestia girls for easiness’s sake. Some of this is based on ‘bad ending’ timelines I had planned out for ‘canon’, some is just. ideas. I’ll do this grouped by storylines effectively. All magical girl weapons are the same as they normally have.
Akira’s wish is ‘I want Mai to be happy’. She’s very enamoured with the hero aspect of being a magical girl so the wish is more of a bonus for her than a motivation. She’s arbitrarily fire-themed - I know madoka powers are normally themed around the wish but I couldn’t think of a way to do that haha.
At some point she and Mai get caught up in a labyrinth and Akira dies fighting a witch. Mai’s wish is ‘I want to go back and stop Akira from dying’. She gains time travel powers - though unlike Homura’s full timeline resets, she gets to rewind time till right before Akira died, then prevent it. She manages to keep Akira and herself alive for several years using this ability, but ultimately there’s an incident where the only way to undo Akira’s death is for Mai to take the hit and die instead. (This technically doesn’t contradict Akira’s wish - since Mai did die happy since she was saving her sister)
Mai’s death causes Akira to turn into a witch. Her witch form is called Brynhildr and has the body of a monstrous dragon + a barrier that’s just. SO much fire.
Rewinding a bit, Izumi’s wish is to ‘have one real friend’. Fortunately for her this isn’t achieved through mind-controlling means, she simply has an encounter with Akira which wouldn’t have happened otherwise. It does mean she’s never able to form truly deep connections with any one else, but that’s bearable - until Akira witches out. Izumi destroys Brynhildr when it appears and when Kyubey tells her who it was, she falls into despair, becoming a witch herself.
Izumi’s witch form, Marina, is a heavily veiled, endlessly weeping figure, like a person in mourning. She lures people into her barrier to be her ‘friends’, only for them to drown in the ocean of her tears.
Clara uses her wish to protect her family from an attacking Witch. She becomes increasingly obsessed with keeping them safe all on her own, and with surviving in order to do so. She ruthlessly hunts down every witch and familiar and chases off or eliminates any magical girl who encroaches on her territory. (in this AU, Clara never joins a team) Eventually she either dies in battle or turns into a witch from not cleansing her soul gem fast enough.
Rin’s wish is to be ‘strong enough that no one can mess with me’. She probably dies sacrificing herself to rescue some other magical girls (Rin doesn’t lend herself very well to total despair).
I honestly can’t imagine Natsuki becoming a Magical Girl in the Madoka universe. She’s too analytical to enter a contract with a mysterious magical creature and I don’t think she’d get so desperate about something for Kyubey to prey on her.
(send me an AU idea and I’ll tell you how I’d fit my ocs into it)