I don't play Pocket Edition although to my knowledge, Drowned spawned from a zombie that was turned into a Drowned cannot drop Tridents. the only way to get Tridents is from killing naturally spawned Drowned. I would recommend searching an official Drowned Farm for PE as I'm pretty sure they exist as I've heard of them in Java/Bedrock.
Beau Bingham
I don't play Pocket Edition although to my knowledge, Drowned spawned from a zombie that was turned into a Drowned cannot drop Tridents. the only way to get Tridents is from killing naturally spawned Drowned. I would recommend searching an official Drowned Farm for PE as I'm pretty sure they exist as I've heard of them in Java/Bedrock.