Yes, he was trained by Mapleshade, who is a Dark Forest warrior. He was simultaneously trained by Cedarpelt, a RiverClan warrior.
No i don't think she will. Ivypool (as a warrior) found out that Dovewing (as a warrior) has the power of the stars in her paws. Jayfeather and Lionblaze ask Ivypool to spy on the Dark Forest cats for them when Dovewing tells them that Ivypool had been training in the Dark Forest. Ivypool seems disgusted with how the Dark Forest cats are training, so no, i believe she will stay loyal to ThunderClan and fight beside them when the Dark Forest attacks.
Yes, Mudclaw is in the Dark Forest in the Warrior Cats book series. He joined the Dark Forest due to his anger and desire for revenge against other Clans. Mudclaw appears in the Dark Forest in "The Last Hope" during the final battle.
Antpelt is a member of the Dark Forest in the Warriors book series. He was a warrior of SkyClan before his death and subsequent recruitment by the Dark Forest.
Ashfoot's the WindClan deputy. She hasn't died yet.
Tigerstar trained Lionblaze in the Dark Forest, manipulating him to become a powerful warrior with dark intentions. Tigerstar exploited Lionblaze's potential and desire for power to further his own evil plans.
No he didn't because he was a loyal warrior when he was alive.
He went to the Place of No Stars or also known as the Dark Forest
The Clan's have had many enemies, such as BloodClan and The Dark Forest.
The dark forest attack occurs in the third book of the Remembrance of Earth's Past trilogy by Liu Cixin, titled "Death's End." It takes place as part of the narrative where humanity faces a threat from another alien civilization known as the Trisolarans.
So far she is a loyal warrior in ShadowClan still. Her brother fights in the Dark Forest, and so far this has not affected her.
He claims of not knowing that his warriors participated in Mudclaws rebellion.
Hawkfrost trained Ivypool in the Dark Forest, manipulating her to turn against her own Clan, ThunderClan. He took advantage of her desire to prove herself and gain recognition, ultimately causing her to betray her Clanmates.