Elite 4 team help

Hey guys, I just beat Nyx/Giratina and I have heard that the Elite 4 is extremelly challenging. Here is my current team and I was wondering what suggestions y’all have to improve my team, so it is better for the elite 4/champion battles. Also what level is the lowest the elite 4/champion can go, since they scale levels with your team. Thanks! Mew (Lv. 84, Synchronize, w/ Rocky Helmet) Moveset: Psychic, Calm Mind, Substitute, Flamethrower.

Excadrill (Lv. 84, Sand Rush, w/ Choice Band) Moveset: Iron Head, Earthquake, Rock Slide, Rapid Spin

D. Snorlax (Lv. 84, Thick Fat, w/Leftovers) Moveset: Wood Hammer, Shadow Claw, Belly Drum, Return

D. Bisharp (Lv. 84, Defiant, w/ D. Bisharpite) Moveset: High Jump Kick, Power-Up Punch, Blaze Kick, Sky Attack

D. Venusaur (Lv. 84, Psycho Call, w/ Metronome) Moveset: Calm Mind, Psychic, Dark Pulse, Moonblast

D. Gardevoir (Lv. 84, Lightining Rod, w/ Expert Belt) Moveset: Thunderbolt, Dazzling Gleam, Livewire, Ice Beam

I am willing to add or remove team members if it will help me. Thanks again!

I suggest running Play Rough, Seed Bomb, and Body Slam on your D. Snorlax and changing its ability to Thick Fat. Mine solo-ed London with that move-set and Power Belt training (lowers speed for higher defense). Otherwise looks ok, just watch out for Reruka’s Mewtwo.

Thanks, I already beat the team with the team listed above though. I had no deaths until reukra which took me a couple tries. His mewtwo and delta volcarona could almost ohko my whole team

How does my team need improvement?
Typhlosion Blaze 88 with Wild Charge, Blast Burn, Eruption and Solar Beam.
Tyranitar Sand Stream 78 with Stone Edge, Earthquake, Hyper Beam and Fire Blast.
Serperior Overgrow 83 with Leaf Storm, Dragon Pulse, Frenzy Plant and Solar Beam.
Metagross Clear Body 88 with Psychic, Meteor Mash, Hammer Arm and Hyper Beam.
Feraligatr Torrent 100 with Superpower, Hydro Cannon, Hydro Pump and Thrash.
Garchomp Sand Veil 100 with Crunch, Dig, Fire Blast and Dragon Rush.

Let me know where I need to change things please.