Board Thread:Naruto Discussions/@comment-26993711-20170203042053/@comment-30323490-20180207162725

Sasuke was able to summon his Hawk in the lava dimension, so summoning clearly works. And reverse summon is exactly as the summoning technique. It's just that a human is summoned by an animal. If Naruto is in another dimension, than yes, Fukasaku can summon him back to earth, just like Sasuke did with his Hawk. It's still inter-dimensional summoning in both cases, that was proven to be effective.

The reason why Hagoromo and the other Kage combined their powers is because the didn't have to summon just Naruto and Team 7, but the other 9 bijuu as well. Which probably took a ridiculous amount of power, hence why Hagoromo was aided by the Kage.