How to fix character constantly accelerating in both directions after deceleration Pygame?

I was able to successfully implement acceleration into my Pygame game, but there is a bit of a problem.
Problem is: After the character decelerates, the character will start accelerating in one direction, decelerate and start accelerating in another direction, decelerate and start accelerating in opposite direction, repeating those two things endlessly. How would i get this to stop?

How can I make an Image with a transparent Backround in Pygame?

I am fairly new to programming, so I bought the Book “Python Crash Course” by Eric Matthes. Recently, I decided to recreate the Pokemon Battle System in Pygame. So far, I have made a good enough framework to start the battle system. I picked the Pokemon Mew as a test subject. I already have the transparent backround for the picture, but pygame still shows the gray and white squares. This is my main code-file:

Trying to delay a specific function for spawning enemy after a certain amount of time

I am making a mole shooter game using pygame. I want my mole to spawn at a random position after every 1 second. I have tried using time.sleep(1.0) but that delays my whole code and thus the game doesn’t function properly because of delayed responses. I am moving an aim using the mouse(which also gets affected because of time.sleep) to which i will be adding a click to shoot. I need help with delaying and spawning my mole. I would also like some opinions on how to organize my code to provide various levels of difficulty and a main menu later on.