I disagree that people are constantly trying to take him down, but let's just assume that's true. If the phone call wasn't incriminating, why try to hide it? Had Trump believed what he did was ok, he wouldn't care about it getting leaked
You hold a meeting, get your party to write up a bill, get congress to vote on it.
TBH, the president probably could investigate a past admin's crimes without congress, and nobody would kick up much of a fuss about it. I wouldn't see it as a problem, as long as it wasn't obviously for personal gain.
What exactly is the scandal there? Yeah, the company probably just wanted to say the veep's son worked for them. It was nepotism. But how is that corruption? We're talking about a private company here, not a position in the Ukrainian government.
But this isn't happening because they don't like Trump. He very obviously broke the rules here.
The point of having laws is to keep people from doing things that harm society. If our attitude is that the voters will get rid of a corrupt president, then the president is basically free to break all the laws he wants until he's not president anymore.