As you know, the Spy from Team fortress 2 have the ability to backstab. Combined with Funky movement or jukes. The spy can pull off a cool stab or Trickstab. The spy will do a trickstab when being chased or got caught by the enemy. Spy will tend to use their surrounding or movement to perform a trickstab.
In this guide i will tell you some Tips and Tricks on how to counter Trickstabs. This guide applies to all class and not just a single class. There will be no "With this class you can-". Anyway lets get to it

1. Keeping in mind about stairstab, cornerstab or teleporterstab, and other stab
This first one is kinda obvious but anyway, Keep in mind that Spy will always bait someone when about to trickstab. This can be countered by seeing where is the spy going. Is it to a stair, a tele, or a corner. This should be a warning, you are better off waiting on the other side or notifying your teammate.

2. Predict their movements
Predicting enemies movement is a crucial part to countering them. This applies the same with Trickstabbers. Predicting their bait or when they will trickstab, can give you and advantage to counter them. Some spies will stop at the top of stair to perform a trickstab, and etc.

3. Learning your enemies
Not every spies can be countered easily. So what you want to do is learn about them. Are they pro or not, do they know a certain stab or not, is he aware of his surrounding or not. Like that. This can also be useful info for your team to know what to expect when chasing spies.

1. Move weirdly when chasing a Trickstabber spies.
Just move stupidly lol. The biggest part when doing a Trickstab is predicting your enemy,. But, if you cant predict them then its hard to do. So yeah, just move randomly. Like random stop, strafing, etc.

2. Standing still when about to be trickstabbed.
yes i know this sound stupid but it works. Just like the first trick, standing still can be viable on countering spies. They will never expect for you to stand still.

3. Try to make the Spy panic
This is hard to explain but just make them scared by like shooting before going to a corner, airblast the ♥♥♥♥ out of em, Lowering their health and etc. Just do the things that make them not want near you.

Well i hope this guide is helpful. I might update this guide someday but knowing myself, maybe not. So yeah good luck on killing spies. Thank you for reading this.
Also don't forget to rate this guide.

For those ppl who say spy can use gun, this is for Countering The Trickstabber. Maybe ill make another on just How to counter spy. Who knows