Like let's get started. Let me just start looking through all generations and picking them out. Bad takes that are well established, popular opinions:
Charizard being the coolest Kanto starter Pidgey being cooler than Spearow Hitmonlee being cooler than Hitmonchan Flareon hatred / it being the most hated Eeveelution Kabuto > Omanyte Chikorita hatred, even from an aesthetic standpoint Lugia > Ho-oh Gen 3 starters being the coolest trio Blaziken being a cool, or even acceptable, Pokemon design Liking Manectric more than Luxray Metagross being the most popular pseudo-legendary Gen 3 box legendaries being better than other generations Turtwig and Chimchar being more popular than Piplup Rampardos never being talked about as one of the coolest fossils Rhyperior being an ugly design Tepig hatred General Gen 5 hatred Pidove being one of the least popular regional birds Archeops hatred Exaggerated Vanillite hatred Froakie being more popular than Fennekin Pumpkaboo never being talked about Not acknowledging Gen 6 for having the coolest box legendaries Weird Popplio hatred for its feminine design Weird Mimikyu obsession Unfair hatred of Kommo-o Lokix and Tinkaton love Liking Violet paradox forms more than Scarlet paradox forms Miraidon being more popular than Koraidon