Will Dark Tuners and Synchro monsters be available in the United States?

It's important to clarify that "Dark Tuners" is not an official card type in Yu-Gi-Oh!. You might be referring to "Dark Tuners" which are a specific set of monsters with the "Tuner" attribute and usually Dark attribute, often used for Synchro summoning.

Synchro monsters are a very important part of Yu-Gi-Oh! and have been available in the United States since their introduction. They are printed in many sets and available for purchase from various retailers.

Therefore, both Dark Tuners (the specific monsters) and Synchro monsters are absolutely available in the United States.

If you have further questions about specific cards or sets, feel free to ask!