Professor Oak is standing behind the Charizard and stepping on its tail. Due to camera angle, he is looking 1-2 inches shorter here. Oak is actually average height of a male japanese adult, 5'7". (I verified it when he was standing as tall as Rapidash in other frame).
In this specific part of the anime, Professor Oak is showing and veryfying whether pokedex data and Information is true or not, to us fans). In one scene, Gardevoir actually shown to made and controlled a literal black hole. She was controlling its size too.
In regular anime show, Charizard is as tall as Dragonite (7'3" or 221cm). But since here Oak is veryfying pokedex data, writer and animator drew Charizard to its specific average correct pokedex height. But in other parts of anime, Charizard is freaking big like in 2nd slide. I think writers and animators said ~a curse word~ and be like: this dragon can't be that small; when they seen Charizard in game is only 5'7".
by Embarrassed-Tea-4217