KVBSA bat standards = USSSA bat standards with no exception. If USSSA approves a bat, it may be used for league play. If USSSA does not approve a bat, it may not be used. You can read the details by clicking the link.
As far as DeMarini bats, an audit of their bats found that several do not meet the standard despite having the proper marks. Those bats may not be used in USSSA and KVBSA league play. For details on which bats, read the DeMarini Bat Announcement. If you own one of these bats, you will want to check their website for their return policy.
As stated in the KVBSA rules, team managers are responsible for enforcing bat rules. Prior to the start of play, the manager from each team should identify which bats are legal and remove from the dugout any bat identified as illegal. If a player is found to be using an illegal bat, that bat will be removed from play at that point and play will continue. If that bat is used again during the game, the manager or head coach of the team will be ejected and the bat removed from play.