They are Lv10, and so require two tributes.
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Two.
Assuming the monster doesn't have any special text which explains how to summon it, then a 10 star monster just requires two tributes, because Lv7+ monsters need two. The Earthbound Immortals and Andro Sphinx/Sphinx Teleia are Lv10 monsters that are tribute summoned as normal with just two tributes.
2
Unless they are monsters that are special summon only, level 7+ monsters require 2 tributes.
As per the basic rulebook, you need two tributes for monsters of Lv7+. Some high level monsters have rules text to say they require three tributes, but these are exceptions. In the case of monsters like Yubel (Lv10) they still only require two tributes.