Genoci gave his opinion on Pokémon you shouldn’t use in a casual RBY playthrough. He established the criteria for his choices (such as when they’re available and their stats compared to others). As you watch through, you’ll see that he’s picking Pokémon that have better alternatives available. I think that’s fair and it also shows why so many people have the same teams when they play this Gen 1.
In the end, Genoci marked 41 Pokémon as the most viable with 8 as backups. Out of 151, that’s not super great. But of course, you can use whichever Pokémon you want and that’s the beauty of Pokémon—you can make almost any team work.
