The way to beat Trump is to highlight his lack of understanding of the political system and how it differs from Business and to force him to talk about his political policies. Many Americans honestly believe that the world begins and ends in the USA and have little understanding of a larger world view.
Trump is a TV personality and that carries massive weight with many Americans who believe fame is important, he is great at marketing and self promotion, but has no real understanding of politics or how the political system works and firmly believes that what works in business will work in politics, which isn't the case as they have very different objectives.
Business is all about profit, in fact in most countries businesses have a legal obligation to maximize their profits for shareholders and this is what drives the decisions of the board members. Politics on the other hand has to deal with many competing objectives, again many of these have legal obligations, energy provision Vs environmental laws is a good example. As the president and chairman of the Trump Organization he can act as he likes (with-in the law) when it comes to policy and the hiring and firing of staff, as President of the USA he would be limited in this, while he can appoint some senior people, other will need to be vetted and agreed by Congress. In politics there are far more checks, balances and counterbalances than he will ever have come across as the boss of a massive company, will someone who is used to saying "do it my way or else" be able to handle the restrictions imposed on him by the political system. Democracy is about compromise where as business is all about competition.
A good example of Trumps Business over politics philosophy is clear in this and other interviews with the
NY Times where he says things like this, when asked about his political appointees "I think about a U.N. ambassador, about a secretary of defense and secretary of treasury, but I think more about winning first, otherwise I’m wasting time. I want people in those jobs who care about winning. The U.N. isn’t doing anything to end the big conflicts in the world, so you need an ambassador who would win by really shaking up the U.N”.
The above quote also highlights his lack of understanding about the power and influence of the UN, the UN doesn't have the power to "end the big conflicts in the world", appointing someone to the UN who can "win" is pointless, what can they win when the UN has no power to change things without the will of sovereign governments, that is extremely clear when one looks at recent history.
As for his plans mentioned in the post above, Building walls, deporting illegals (in some states up to 20% of the work force and 10% in many others), unilaterally scrapping trade deals and the rest, he seems to have forgotten that he is only President not Emperor. His power will be greatly weakened by the bureaucracy, Congress and historical precedent.
His lack of understanding of how the political system works should be clear for all to see and if his opponents stick with this and policy issues he should be finished very quickly, alas I fear they may be dragged down to his level of personality issues and leave the door wide open for him.
(the above while having a pop at Trump shouldn't been seen as support for Clinton, I think they are both as bad as each-other).