i'd do Slowbro but I already have Staryu which will become a Water/Psychic type when it evolves and I don't want two Water/Psychic types Lapras and Snorlax are as easy to obtain in Yellow as they are in Red and Blue; as in, a gift Pokémon and a forced story encounter (albeit one with a low catch rate) respectively I have a Chansey in my PC box and I'd use it but it's pretty bad without TMs