Ok, so EVs are pretty important and can make e4 a lot easier and you also want to make sure to have your entire team at the same level
Typhlosion- Eq is pretty useless on it bc of it’s lower attack, solar beam isn’t good without sun, and inferno is inconsistent and isn’t worth the accuracy for 100 bp. I’d replace these moves with extrassensory, hidden power, and flamethrower. HP/Extrassensory for coverage and flamethrower for when you have low hp/run out of eruption pp
Gatr- set seems fine although the nature is awful and it’s better off with it’s HA (sheer force)
D. Gallade- replace thunderbolt with wild charge or thunder punch to hit physically and permafrost to some other coverage since you’re using more of a sweeping set. The mega stone could be replaced with another item of choice.
D. Zard- Dark matter is pretty bad on zard as the coverage is useless tbh. Also since zard is a special attacker, I’d recommend using sludge bomb, shadow ball, ice beam, and draco meteor/dragon pulse. I’d also recommend replacing the mega stone with choice specs as it’ll hit harder with coverage moves and noctem isn’t very useful on your team. The nature is also very bad but I think you can still make it work if you’re on normal.
Lucario- dragon pulse/reversal is pretty useless on it so I’d just use swords dance along with meteor mash/iron head for stab
Chomp- Slash is an awful move and it should probably be replaced with any other coverage like fire fang/poison jab/rock slide. Dragon rush could be replaced with outrage/dragon claw for a more accurate stab and the mega stone should be replaced with life orb/expert belt to get the most out of reg chomp’s better speed.
So yeah, as IndianAnimator said, what do you want to build around? I personally would build around Feraligatr, though I would try to get a Jolly or Adamant one. Lucario is probably the only salvageable mon here, and it’s not great. I would get a Scizor, Adamant or Brave. Taunt is p mandatory for Kayla, unless you’re carrying Leech Seed and Clear Smog/Haze.
In my experiences, Gengar (regular one), Excadrill, Scizor, Choice Scarf D.Gallade (if played Jolly), Mega Kangaskan, Mega Typhlosion (never tryied but seems OK), Armored Tyranitar and Hydreigon are great against the elite four. They would need proper surrounding, so don’t think you can put all of them in one team.
Do not forget you need to train your Pokémon at the same level so you don’t have level disadvantage against the E4.