Simply put: SOS Chaining
If you keep up a long enough chain, there's a chance that the Bounsweet called will have its hidden ability. Specifically, after 10-19 Bounsweets, theres a 5% chance of it having its Hidden Ability. 20-29 brings it to 10%, and 30+ puts it to 15%. But since you have no way of knowing whether it has the right ability or not, I'd recommend getting a Parasect, and teaching it False Swipe, Spore, and a damaging move. Sweet Veil prevents sleep, so you can use Spore to tell, and False Swipe keeps the chain in motion.
Hope I could help!