This gameplay footage shows off the basics of one character combat. There are points in the game when one character will be left to fight alone until others join the party. Such is the case of this battle . . .
In this case the single combatant combat scenario happened due to the game's new random battle feature. Think of it as being like FFVII's random battles that happen as you move from area to area. The only difference being that in "Zero Dimension Neptunia Z" you'll travel dot by dot in a line from area to area while occasionally running into a group of lesser enemies. Beating them will get you back onto the map where you can continue traveling to the designated point of interest.
As far as combat goes it is turn based, and offers the players a variety of different options including attack combos, skills, defense, item usage, and HDD transformation in which the CPUs turn into their CPU Goddess form. Knowing when to heal, when to fight, and when to defend will mean the difference between victory, and a 'Game Over'. Supposing you come out victorious you'll reap the rewards in the form of experience points, credits (the in-game currency), and possible materials that can be used to craft special items. The end results also keep records of your combo count, and damage points.
As with the other features of the game the basics, and more advanced features of battle are explained in detail by Histy in the "Teach Us Histy!" tutorials.
Combos are achieved by linking together unlockable (unlocked through repeat use) combo traits from the base 'RUSH (TRIANGLE)', 'POWER (SQUARE)' & 'STANDARD (X)' attacks. In order to initiate said attack combos you must first position your character, and her outward facing weapon target guide towards the enemy. Depending on the weapon the characters are wielding they can hit single, or multiple enemies at a time as long as they are within the weapon's target guide range. Once initiated via the combat menu option you'll have to press the attack type of choice. Combos are limited according to weapons, and which combo strings you choose to use. You can mix & match them as you see fit though. Just keep in mind that 'RUSH' is the weakest, 'POWER' is the most powerful, and ''STANDARD' is normal in the way of damage output. Of course as you unlock more combo traits you will find traits that do more damage. Linking them together via the "Combo" menu in the most efficient order will help you to dish out the most damage possible. Some combo traits are also elemental in nature, so using them on certain enemy types will be more beneficial.
Like combos the skills in the 'Skills' combat/main menu are unlocked through repeat skill usage. The more you use a skill in combat the more of them will become available. Skills in this series use up energy that is simply known as "SP". The 'SP' can only be refilled by certain restorative items, unless otherwise detailed in the pre-battle 'Teach Us Histy" explanation. The available skills are character specific, and range from animated attacks to character stat boosts, protection, and even healing. There are even HDD Goddess form skills that can be used while the HDD transformation is active. I'd say from experience that skills are best used against bosses, and harder to defeat enemies.
The HDD transformation, or CPU to CPU Goddess transformation is a limited use ability that comes into play once you build up your EXE meter. The EXE meter is built up by dishing out attack combos upon enemies, either through combo attacks, or skill attacks. The HDD transformation is best utilized when facing bosses as it is the CPU's, and CPU Candidate's most powerful form. With that being said the EXE meter does reset after each battle though so using it when it's available is not a bad thing.
COUPLING & FORMATION:
Two of the key elements in multi-character combat are "COUPLING", and "FORMATION". Coupling in the combat, or battle system sense is basically linking two characters together for an added effect for the leading character. To tweak this you have to go into the main men's "PARTY" menu, and choose the "COUPLING" sub-menu option. Once there you can pair up characters, and set their coupling traits to either 'defensive', or 'offensive'. The 'defensive' setting boosts things like VIT, and DEF stats. The opposite is true for 'offensive' which houses ATK, and TEC stat boosts.
Along with the 'COUPLING' option you'll also build up what is called 'LILY RANK'. This is basically the relationship level between paired characters. The 'LILY RANK' also allows for special boosts, and skills among paired characters. Aside from that the 'FORMATION' sub-menu within the 'PARTY' menu will allow you to strategically place your characters in positions on the battle grid so that they'll either dish out more damage, or take less damage. Placing characters up front boosts their attacks while positioning them in the back causes them to take less damage.