i have been requested to make a deposition but not subpoenaed, is there a reason to wait for subpoena or cooperate?

There's no real reason to wait for a subpoena except that if your testimony goes against somebody they may be less mad at you since you had no choice but to testify.  It may also help you if you need to get the time off work to go testify.  The only other reason to wait for a subpoena would be if you had a non-disclosure or confidentiality agreement which would conflict with your testimony, which doesn't seem to tbe the case here.