this may be a remedial question, but can a cb plan have a vesting schedule that isn't as good as a 3 year cliff? (1-25%, 2-50%, 3-75%, 4-100%)

If we are talking about a CB plan (or other hybrid) designed to fit as an "applicable defined benefit plan" under PPA section 701, the minimum vesting requirement is 100% at 3 years. New IRC 411(b)(5).