I haven't seen anyone complaining about the Shiny Beasts who appeared in the Zoroark movie and yet, according to the legend of Ecruteak City, Ho-oh brought life to a trio of Pokemon who perished in the Burned Tower (former Brass Tower). So what happened? Other Pokemon, which were coincidentally in trios and died in multiple burning towers, where brought back by Ho-oh as the same species of the first resurrected? Why didn't them become of other types, like Grass or Psychic?
There are a lot of things that don't make logically sense in Pokemon. Another Mewtwo is one of those things.