Nagato wins all scenarios. High difficulty for scenario 1 and low-mid difficulty for 2nd and 3rd scenarios, if he chooses to take them out with CT out of character.
The speed combo wouldn't work. The combo only landed a hit on Edo Madara, due to Mei's strategy to nullify Rinnegan field of vision with the mist; without the mist, the combo would have failed to land a hit. Unlike ET Madara's circumstances, Nagato can nullify the mist with the following: He can fly and sense so the probability of blitz is literally null. Not to mention with his possession of gravity, he can slow down their momentum to the point he can predict their movements. The speed argument is honestly invalid for stated reasons. Besides that, Taijutsu is a literal suicide against Nagato. Asura Path would catch them steady and Human Path rips their souls out.
Gaara's sand is useless to Nagato because of this
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: it spits foam which is superior to oil, because it washed off Jiraiya's oil on Konan allowing her to utilize her paper. Gaara's sand weakness is oil, so the foam would liquefy Gaara's sand and it becomes useless from that point.
Mei and Tsunade aren't worth addressing.
Some say Gokage pushing ET Madara to use PS means they beat Nagato, while forgetting Rinnegan pinnacle movesets are superior to everything ET Madara used in his fight with them. Nagato can counter everything they can throw, while Gokage fail to prove they can counter the Rinnegan, even with intel they have.