His friends would be devastated. May, for instance, would probably be in deep shock and denial at first. She might remember all the times they had competed and the little moments they shared. Then she would likely turn her grief into determination to carry on his legacy in the Pokemon world.
Well, his friends would have a range of reactions. Some would be inconsolable, crying for days. Others might try to be strong on the outside but be secretly broken inside. They would start to reminisce about the good times with Drew, like when he showed off his new Pokemon techniques. And they would all vow to keep his spirit alive in the Pokemon community by being better trainers and kinder people.
Moka would be devastated. She has a strong bond with Tsukune, and his death would likely send her into a deep state of grief and anger. She might go on a rampage seeking revenge against whoever or whatever caused his death.
His friends would be extremely shocked at first. Misty might scream and be really confused about what's happening to Ash. Brock, on the other hand, would probably try to stay calm and start thinking of ways to reverse the transformation right away. They would all be worried about how Ash is feeling in his new form and if he's in any pain. They would also be concerned about how they can still communicate with him effectively, since he's becoming a Pokemon.
May could be completely surprised. Given that Drew has always been a bit of a rival and a bit aloof at times, she might not have expected his confession at all. So she could just stand there, mouth agape, not knowing what to say at first.
Ron might see it as another adventure that Harry is having and would be eager to join in, even if he doesn't fully understand it at first. He'd be excited to see the different Pokemon and might even try to catch one with Harry. Hermione would approach it more analytically. She'd question how the Pokemon world operates, what the rules of Pokemon training are, and how it could potentially affect the wizarding world. She might be a bit worried about any potential negative impacts.
His friends might be really confused at first. Pikachu, for example, might give Ash some really puzzled looks. If Ash tries to explain to his friends that they're all part of a fanfiction, some of them might not believe him at all. Misty could think Ash has hit his head or something and is just spouting nonsense.
Ash would be completely devastated. Pikachu has been his closest companion since the start of his journey. He would probably go into a state of shock at first, unable to believe that Pikachu was gone.
One possible plot could be that Drew, in the fanfiction, dies while on a dangerous mission to protect a rare Pokemon. Maybe he encounters a powerful and evil trainer who has no mercy. His death could then inspire his friends in the Pokemon world to fight even harder against the forces of evil.
Hermione would be heartbroken as well. She would likely try to find a way to bring Lupin back, delving deep into the library's restricted section for any possible spells or solutions. She would also be the one to comfort Harry and Ron, using her logic to try to make sense of the senseless loss.
His friends from Team 7, like Kakashi, would feel responsible for Naruto's situation. Kakashi would likely use his resources to find a proper shelter for Naruto. Shikamaru and the others might come together to form a sort of support group for Naruto. They would pool their resources, like money and food, and also try to cheer him up by sharing stories and jokes.
His Pikachu would probably be very supportive. It would stay by his side as he studies, maybe even help him in small ways like fetching medical tools. It trusts Ash completely and would be happy to see him pursue something new.