If you haven't listened to Mystery Show, the podcast where Starlee Kine solves unusual mysteries, you should. You can enjoy the episodes in any order. I recommend starting with episode 5, "Source Code," in which Kine tries to solve the mystery of actor Jake Gyllenhaal's height.
What does this podcast have to do with the list of Pokemon discrepancies mentioned in the headline? They both celebrate fandom and the unique pleasure of sweating the small stuff.
After you listen to that episode of Mystery Show, you'll be primed for what I believe is the internet at its most internet-y: a list of 34 size discrepancies in the Pokemon anime. The collection is part of Bulbapedia, one of the web's most lovable rabbit holes.
Contributors compare the officially documented heights of pokemon with their perceived heights on the long-running cartoon. Discrepancies in pokemon height are listed in alphabetical order, beginning with Articuno and ending with Whismur. I've selected a few of my favorites, but really, the list is better enjoyed holistically as a monument to fandom.
Charizard are usually 5'7" (1.7m) tall, but Ash's Charizard is taller than that, at about 7'00" (2.10m) tall. Oddly enough, it is shown in Charizard's Burning Ambition that Ash's Charizard is rather small when compared with the Charizard living in Charicific Valley. Also, in Grating Spaces!, a Charizard was shown to be as tall as an Aggron, 6'11" (2.10 m).
One of the more renowned changes in size is in Roselia, which are extremely small—only about a foot (30cm) tall. However, the Roselia in the anime come up to a 10-year old's waist. An estimate would put the anime incarnation of them at about 3' (90cm) tall. This caused much confusion when Pokémon Colosseum and Pokémon Adventures both featured the Pokémon at its actual smaller size.