>>42711023because if he's slept and swapped out, he can swap back in and spam Fishious Rend through sleep
It's a niche thing but it's the most useful 2nd move to have on Dracovish. In doubles, say dracovish gets slept by Butterfree or gets hit with Yawn and is put to sleep, you can switch him out and bring him back in late game as a win condition since he's probably sleeping for 2 turns and that's all you need to spam sleep talk and sweep with Fishious Rend.
Dracovish using moves other than Fishious Rend is really fucking weak though. Yes, Crunch and Psychic Fangs get boosted to about 120 BP each, but that's not a lot when it's not STAB and it's with a base 90 attack. In almost all situations it's better to just use Fishious Rend unless it's vs a Storm Drain/Water Absorb pokemon.