are we talking about physical elements that are know to exist or ones that are subject to speculation in only a couple of papers?
Ones with atomic number >103. Whether they exist or not is a grey area. They can generally be "made to exist" for short periods of time. I'm not sure whether it's fair to include an element just because it *has* been made to exist (for a millionth of a second) and exclude another because they couldn't decide whether made it exist or not. Anyway, scientific theories have a place in Wikipedia, right or wrong - provided they have been published in reputable journals.
Question: Are there any "reputable" sources that publish articles about Pokémon characters?
Steve