Question: xcom 2 how to train psi?
Answer: Step 1: Obtain a Sectoid Corpse. The Sectoids are the large, fleshy aliens with mental powers. ... 
Step 2: Research - Sectoid Autopsy. ... 
Step 3: Research - Psionics. ... 
Step 4: Build the Psi Lab. ... 
Step 5: Train a Rookie to Become a Psi Operative.