There are a ton of viable wallbreakers in NU alpha right now, though as 5qwerty suggested some of them are likely to be banned. Clawitzer, Kingdra, Tyrantrum, Delphox, Crabominable, Gallade, Jynx, Alolan Golem, Noivern and Dragalge all come to mind as being able to run viable wallbreaking sets. Though I can almost 100% assure you that 1/3 if not more of these threats will either rise in usage in RU or be banned within a few months. Particularly the Dragon types I listed.