Shiva — Battle Intel Report 05
Ice queen Shiva has barely changed from her 1997 form, and makes up part of the classic elemental team — only Ramuh and Titan are missing to complete the five base elemental summons in Final Fantasy VII Remake.
Shiva is also the first Summon Materia that can be obtained from Chadley through his Battle Intel Reports, as early as Chapter 3, and can be a tough fight. Simply select VR from Chadley's menu to start the fight.
Shiva — Boss Fight Strategy
If you're tackling this one as soon as it pops up, you might want to wait until you have Aerith (and her awesome magic power) back in your team.
As always against Ice-types, Fire is your friend. Hit her with Fire spells as much as possible, on both characters — she's somewhat resistant to physical attacks, and it can be quite a chore to even get close enough in the first place.
When she summons Frost Familiars, make sure to take them out as quickly as you can using physical attacks. They negate magic damage, which is detrimental to your maximum damage output.
Naturally, keep yourself healed — Shiva's Diamond Dust ultimate can deal upwards of 1000 HP damage, instantly wiping your team. If you're having trouble with the amount of damage she is doing, set up the Fire Materia + Elemental Materia pairing on your character's armor.
Finally, use Ifrit as soon as he becomes available!
This battle is more a grind than impossible, but with the right setup you should take her down in the end.