As confirmed from the higher ups, the only two bosses that have a chance to give shinies are Pumpkin King & Naero. You were correct in saying it was declared for the other bosses.
To you and the rest of the people in this thread, this thread quickly got off topic. This is General Support, meant only for the question and answers. Please refer yourself to the forum rules.
3. Toxicity towards users and community as whole will be sanctioned and discipline measure will be taken.
Please refrain from using insults on each other in the future. We're here to help and not belittle people for not knowing the answers. Hope this helped!