Trumptale is an AU where every monster resembles Donald Trump, Frisk is Mexican, and the AU is sort of like Underfell, but not as bad. Flowey is Barack Obama.
Long ago, the earth was ruled by humans and monsters. However, a man named Donald J. Trump managed to convince the monsters that the Mexican humans were planning to get rid of them, thus starting a war. However, the Mexicans won, and the monsters, along with Trump, were forced to retreat to the Underground. After they were all secured, Trump built a wall to keep the Mexican humans out of the Underground. Trump grew crazy down there (As if he wasn't already) and he made every single monster resemble him. He proposed to stage a revolt on the Mexican humans, and due to his unlikely motivation, was elected as King of the Underground.
About the AU
Every monster also hates humans too, but none of them are truly evil, nor are they good. Many of the monsters are racist and will only go after Mexican humans. When Frisk arrives, the monsters are planning a revolt, then they become aware of Frisk's presence. Frisk's goal is to show the monsters that not all Mexicans hate them and encourage them to achieve peace.
Like Underfell, Flowey, who in this case is Barack Obama, will guide you through the Underground.
Frisk is a Mexican
Toriel is Trump (yes, Donald Trump, not Melania, or Ivana, she is literally Donald Trump)
Sans is Trump
Papyrus is Trump
Undyne is Trump
Alphys is Trump
Mettaton is Robo-Trump
Asgore is King Trump, aka the true Donald Trump.
Asriel is Donald Trump Jr.
Flowey is Barack Obama
Chara is Ivanka Trump.