First of all, it's a bit weird because the battle type may not be what was set originally: Surprise is converted to initiative if the battler placement is "manual" or there is only 1 actor in the party. Pincers is converted to back if the battler placement is "manual" or there is only 1 enemy in the monster group. (Including the different effects on calculations explained below!)
It affects the placement of the battlers of course (position and mirroring).
- If initiative battle or surprise battle (same as if "first strike" flag is set): Escaping via fight/auto/run menu possible during first turn; "Caught the enemy off-guard" message displayed at battle start
- If surprise battle: Enemies attempting to escape always fail (their escape action is converted to a "do nothing" action when executed)