6th member for my team

Building a team in Pokemon Shield. Here is what I have so far...

Lapras - Modest
Freeze Dry
Ice Beam
Hydro Pump
Perish Song

Gengar - Timid
Shadow Ball
Slude Wave
Focus Blast
Destiny Bond

Snorlax - Careful
Crunch
Body Slam
Earthquake
Curse

Haxorus - Adamant
Poison Jab
Earthquake
Outrage
Dragon Dance

Ferrothorn - Impish
Power Whip
Leech Seed
Stealth Rock
Protect

What am I missing? Who can help? Sorry if there is a separate section for these types of questions.

Is this for online? Having the ev spreads and whatever unique abilities would help.

Ferrothorn wants Gyro Ball especially with fairies like Grimmsnarl everywhere.

The sole observation I have is this team struggles with defensive Corviknight, especially the bulk-up->substitute. Haxorus unfortunately only gets one fire move(its not physical). I'm sure the typical suggestion would be Rotom-H especially with the lack of electric type moves here. Its just the typical Corvi switch-in so people are prepared for it however..Its great for the pivot volt-switch though.

I also don't see a (direct) answer for opposing Ferrothorn either except for focus blast Gengar(which funnily enough after discussing Gyro Ball, doing the calcs Focus blast is a 30% chance to miss attack that only 2HKOs Ferro but Ferro has a chance to OHKO with Gyro Ball uninvested in attack due to the speed difference.)

I just used the sampled EVs the calc gave me but I still think it makes the point:

252 SpA Gengar Focus Blast vs. 252 HP / 36+ SpD Ferrothorn: 106-126 (58.5 - 69.6%) -- guaranteed 2HKO

0 Atk Ferrothorn Gyro Ball (150 BP) vs. 0 HP / 0 Def Gengar: 121-144 (89.6 - 106.6%) -- 43.8% chance to OHKO

If not Rotom-H..Throat Spray Toxtricity is a great Corviknight counter and electric type. It also learns Fire Punch if you go mixed.

Not to be stereotypical, but perhaps a Bold Gardevoir/Gallade?

Held Item: Choice Band or Life Orb
Moves: Calm Mind, Moonblast, Psylock, Reversal (for Gallade), Night Slash (for Gardevoir)