That's an improvement.BREAKING NEWS:
Belch can be used after you switch out; thats right, you can use Belch after you consumed a berry, and switched out with a different Pokemon, and come back.
Also, Belch Gulpin W/ Wish Swirlix are very great partners in Gen VI LC justwantedtotelleveryone.
Other candidate berries that won't necessary leave your HP low include Sitrus, Lum, Chesto, and the attack-type damage reduction berries like Shuca.
ChestoResting with Belch could work now that we know that berry consumption enables the move for the rest of the match.
But the fact that the pokemon is forced to carry a particular item and only mediocre Pokemon get it makes it a pretty bad move still.
Of all the Pokemon known to get Belch Seviper has the highest SpA but its Specs Sludge Wave out-damages unboosted Belch.
So unless it plans to eat a Petaya berry and stay in (and its low speed hinders it) it's better off using a more reliable move.
The more defensive Poison Pokemon that get Belch will miss Black Sludge/Leftovers unless they run Rest which has its own issues.
So Belch will likely vanish into the realm of gimmick moves that everybody forgets after a while.