Board Thread:Naruto Discussions/@comment-34700383-20180829185752/@comment-33485854-20180904113802

LegionZero wrote: It does require merging the Tailed Beasts. This is why Madara/Obito went through so much trouble to seal them in the Gedo and revive the Juubi before becoming its Jinchuriki.

That's a forceful method of combining the Tailed Beats' power. Everytime they're depicted while in their aggregate form you can still see their individual forms twisted together in a mass of Chakra. It is just their Chakra melded together.

LegionZero wrote: Kinda sort of. Sage Transformation doesnt achieve Sage Mode. Its a seperate form of Senjutsu with unique applications and abilities.

Sage Transformation is a reaction the body undergoes at the presence of Sage Chakra. It's Sage Mode in another form once it's fully activated.