Fishing Llanddwyn Island is an adventure in itself. Its a hard slog when carrying your fishing gear, the closest car park is over a mile away. Unless you live local you can actually park quite close to the start, but you need a key.
Llanddwyn Island has lot of marks to fish from, sandy beaches to rocky outcrops. Its ideal for both bottom fishing and a bit of LRF in places. In general you are fishing on to a sandy bottom, not sure I would want to carry both sets of gear though. Definitely keep your tackle to a minimum, this will make the journey far easier.
There are not many reports from fishing Llanddwyn Island, they seem to have slowly disappeared over the last few years.. It may be the long walk that puts people off as there are many easier access marks on Anglesey. That said if its not all about the fishing, the local scenery is on par for best in the UK.
Fishing behind the old lifeboat shed from the rocks, aim straight out parallel to the opening of the bay. This area has the deepest section of water around the island, straight on to a sandy bottom. Lug has always been poor for me here but Razor clam can work well, providing busy sessions as does Rag worm.
Llanddwyn used to be renowned for its smooth hound fishing, I cant see why that would have changed recently. The facebook group Shorehuggers had a meet on Llanddwyn on the 11th of May 2019 and next to nothing was caught. It will fish better mid June on wards as the water temperatures beginn to rise a little more steadily.
Get out and give it a go. Its a venue where you have to work to find the fish but the spot I mentioned above has always produced for me. Its not easily visible so not often fished.