Is there any evidence that both parties agree on?
- Ukraine has a problem with corruption
- There was US pressure on Ukraine to open "investigations"
- Aid to Ukraine was on hold at one point, but was ultimately released.
- I think at one point a Republican (Nunes) and Democrat (Peter Welch) both said "The President can fire an ambassador for any reason whatsoever"
There are also what might be called "basic wiki facts" -- who was in office at this time, etc -- that everyone agrees on. I'm not aware of any notable disputes about such facts.
Investigations is in quotes as it was an explicitly vague term mentioned in the hearings on Wednesday (Nov 13, 2019). It generally refers to some kind of investigation into Burisma in the name of anti-corruption, but also investigations related to foreign involvement in the 2016 US elections.
Jim Jordan pointed out several times (Nov 13, 2019) that aid was released when questioning Taylor. For example
I understand. All right. So again, just to recap, you had three meetings with President Zelensky, no linkage in those three meetings came up. Ambassador Zelensky didn’t announce that he was going to do any investigation of the Bidens or Burisma before the aid was released. He didn’t do a tweet, didn’t do anything on CNN. Didn’t do any of that. President Zelensky, excuse me.
(Here linkage refers to linking aid to "investigations", that is, aid being released only if Zelensky makes a public announcement about "investigations").
Schiff later comments
Some have argued in the President’s defense that the aid was ultimately released. That is true. But only after Congress began an investigation. Only after the President’s lawyers learned of a whistleblower complaint. And only after members of Congress began asking uncomfortable questions about quid pro quos.
edit: I didn't realize at the time, but the above links only show context around the timestamp, not the full transcript, so full transcript link here.