If you don't pick Charmander your best two viable solutions are Arcanine and Rapidash as Flareon and Ninetails have terrible learnsets (not many fire types in gen 1). Charizard also has higher base stats across the board than Blastoise. Also, there are tons of really strong water types you can get in gen 1, like Starmie, Lapras, Vaporeon, and Gyarados.
Although, Blastoise carries through the early / mid to late game when you get ice beam before the 4th gym in Celadon City. The water type is unbalanced in the late game in gen 1, 7th gym being fire and 8th being ground. Also ice beam shits on Lance, Bruno has two Onix', and Agatha has a Golbat (weak to ice). Blue / Red has a Pidgeot (weak to ice beam), rhydon (weak to water & ice), arcanine (weak to water), and venusaur (weak to ice). Only real "threat" is Alakazam who has bad defense / sp. defense stats. He also has a gyarados which isn't much of a threat (although it does know hyper beam, rest move anyways) and ice is neutral against it. In theory, Blastoise can sweep the champion. (Vaporeon can also learn ice beam btw)
And bulbasaur is good early game, against the 8th gym, and you would assume against Lorelei, but most of her pokemon know ice moves so gg.
Party Pooper.
