u/Expert_Log_7309

https://docs.google.com/spreadsheets/d/1J3ba71i965UvCzpQomKLosjjhEUdm22poLQKr-jIwl4/edit?gid=772505263#gid=772505263 doc claims that he can be found in Cerulean cave but when I use the pokedex it doesn't show that he's there. I tried route 12 but could only find slowpoke. Is Slowbro a super rod encounter only or something?