I haven't picked up on what makes this particular thing unique.
I haven't been paying much attention, but I think the gist is that Trump wanted to trash someone (Biden) he figured he'd likely be running against in the presidential election. Apparently, a US politician accepting election help from a foreign nation is illegal.
Also, he attempted to do so by withholding aid money, which seems to be a pretty horrible abuse of power.
Only the last part is notable to me, if he was leveraging something that isn't his to leverage for his own campaign goals, although that's a blurry line that I'm sure every incumbent candidate trounces over to varying degrees.
And the legality of who can assist shady politicians in elections shouldn't be dictated by what country they're from. What's any more ethical about an american business doing whatever it takes to get someone elected in exchange for favorable treatment thereafter than an entity in another country or that country itself doing so? It's all kind of mumped up but ultimately, it's the responsibility of the voters to not be dumbfucks and see through all that and vote for the person who'll best to the job correctly.
I doubt trump needs the ukraine's help to get enough idiots to vote for him. He just has to talk crap about mexicans and blacks at the necessary times.