>>12949726No, because the backstory in the Cinnabar mansion talks about how Mew was supposedly extinct and that they found a single surviving specimen, from which they birthed Mewtwo. After that the mansion was destroyed. Mewtwo escaped to the Cerulean Cave, where it is encountered. Mew more likely fled to its home, which according to Emerald, it did. Ergo, it wasn't available to the player.
