Gozer the Traveler. He will come in one of the pre-chosen forms. During the rectification of the Vuldrini, the traveler came as a large and moving Torg! Then, during the third reconciliation of the last of the McKetrick supplicants, they chose a new form for him: that of a giant Slor! Many Shuvs and Zuuls knew what it was to be roasted in the depths of the Slor that day, I can tell you!
If this nerd has both a fateful encounter Celebi and a shiny fateful encounter legendary beast, he should be able to get both the Zorua in Castelia city and the Zoroark disguised as a human in Lostlorn Forest. Both of them are shitty furbait though