Chapter five is a bit of a change of pace. It's not really any more difficult than previous chapters, but for the first time in Hard difficulty (assuming you're playing along chronologically) you'll have a full party... eventually. Your enemies, while not difficult, are varied, and you'll face foes weak to lightning, fire and ice in this chapter. Most of these foes (with few exceptions) can be defeated with a single cast of base elemental magic, so having a magic-focused (Magic Attack 300+) Cloud with Magnify Materia will simplify things considerably, but you'll need to have fallback elements equipped and be willing to swap out materia as needed.
|Useful Materia:||Lightning + Magnify, Healing, Revive, First Strike, ATB Stagger, Magic Up, HP Up|
|Useful Materia:||Ice, Fire, Healing, Revive, First Strike, ATB Stagger, HP Up|
|Weapon:||Light Machine Gun*|
|Useful Materia:||Ice, Fire, Healing, Revive, ATB Stagger, Magic Up, HP Up|
Note: We swapped from the EKG Cannon to the Light Machine Gun as soon as we had the SP to hit Weapon Level 6. Your ability - or desire - to do so may vary, so if you can't or don't want to use the upgraded Light Machine Gun, use the EKG Cannon instead.
You'll start out this phase fighting Slug-Rays, which are trivial to defeat. Just equip Cloud with Lightning + Magnify and you should have no trouble blasting through the first several fights until you reunited with Barret.
Upcoming fights can get superficially more complicated, as Slug-Rays will be joined by Grenadiers, Elite Grenadiers and Guard Dogs. We still prefer to focus on the Slug-Rays, for now, and keep our Fire + Magnify in place, but tossing Fire Materia on Barret/Tifa (or having multiple elements on your characters) will give you options for dealing with nuisance enemies. There are also two groups of Wererats you'll encounter (one optional, one not) after the Slug-Ray exclusive bits, but it's not worth using MP to deal with them.
After defeating the aforementioned you'll get the Grashtrikes. They can deal respectable damage with their "Sickle Swipe" and "Leaping Slash" attacks, can inflict "Poison" (we equipped Star Pendants so we didn't have to worry about it), and are more significantly affected by the element they're weak to - ice - than most foes on this map. They rarely occur in great enough numbers to really warrant Magnify, but you'll want to keep Ice Materia equipped, as its effects are devastating against Grashtrikes - especially if they barrier up.
The fight with the Queen Grashtrike shouldn't be too bad; kill the two normal Grashtrikes quickly with Blizzard, then focus on the queen.
After the Grashtrike Queen you'll transition back to Shinra troopers, including Security Officers and Flametroopers. Use Fire on the latter to make them significantly easier to defeat, as they can deal relatively high damage with their flamethrowers.
Later on you'll encounter a pair of Flametroopers and two Sentry Launchers. Only one Magnify Materia, so we'll have to choose which to focus on. For this part we opt to go with Lightning + Magnify, as those Sentry Launchers are obnoxious. We hit them with Thunder every time Cloud has an ATB charged, and have Barret/Tifa use Fire on the Flametroopers when they can. Hide behind the shipping crates to mitigate the damage caused by the Sentry Launchers and you should be fine.