Not the Eidolon you’re looking for? Check the full battle guide here!
Your first Eidolon battle in Final Fantasy XIII involves Snow (you have to love the naming irony here). To start out with you need to take out some PSICOM troops. This part is pretty easy, just wait for the ATB gauge to fill up and then hit the enemies with everything you have. If your health gets low, then throw a potion to top yourself up again. This part of the battle is more fiddly than hard.
The next section though can be a real pain in the neck if you don’t know what you’re doing. Basically, you are trying to impress the Eidolon Shiva. Use Libra to identify what will impress her (in this case, enduring attacks and building chain gauges). This means you need to jump between sentinel and commando Paradigms. Most of the time you will be in sentinel mode. Use Steelguard and execute it just before you get hit to defend against the attack. This should cause the gestalt gauge to increase slightly.
When the sister who is attacking you switches it ATB charge, switch to the commando role and aim for a full ATB bar’s worth of attacks. This won’t increase the Eidolon’s Gestalt Gauge much, but every little helps in the battle against Shiva.
Keep up this dance against the Eidolon and eventually the Gestalt gauge will be full. Remember, the label of the gauge is not actually a part of the progress bar itself! So once the gauge reaches the letters, press Square (or X) to finish the battle and claim your first Eidolon in Final Fantasy XIII.
Why not check out the combat guide here?