SQUAT: Training considerations when performing the squat would be how to replicate the movement without the the possible use of limbs, hips, or other joints/muscles typically used when performing the squat. Ball slams, Box-to-Chair transfers, Russian twists, and battle ropes are all excellent movements to build and maintain the midline stability that is required when performing a traditional squat.
DEADLIFT: When adapting the deadlift for the seated athlete, ultimately your goal is to find anyway to get an object(s) from the floor to your lap. From the front or side, move an object from the floor – (hand on chair for balance/support) and bring the object to your lap. Try using a KB or DB on the side of chair or seated at the end of a bench to allow clearance for the weights. Suitcase holds in a chair and good mornings in or out of a chair are both great foundational exercises for the DL.
OVERHEAD PRESS: The overhead press can be modified in a variety of ways. Vary the pressing movement with static holds and presses and try using different equipment such as the DB, KB, medball, or sandbag. Heavy seated wall balls are also a great dynamic pressing movement.
PULL UP: The pull up (PU) and derivatives of, can be performed using a variety of methods and equipment. Try performing a low-bar or ring pull up from the chair – get a spotter if you need one. Banded ring-rows and pull-downs can be performed in or out of a chair. Also, try bar-hangs, which will challenge your grip – The “Coffland” Hero WOD will most certainly challenge even the strongest of grips. (https://catchaliftfund.org/the-coffland-hero-wod/)Try implementing negatives to increase overall strength.