Umm you can only submit that if Lapras is the next mon for slates provided by the host of this.Whoever said Mega Mothim <bug/dragon> (should be megaFlygon with Megahorn)
So anyways what about everyone's favorite Plesiosaur?
So now let's take a look and examine some of moves that Lapras already gets to see how we might go about a Mega.
Type: Water/Ice
Ability: Water Absorb, Shell Armor, Hydration (hidden ability)
Stats: 130/85/80/85/95/60
Role in team: Support, Physical Set-up Attacker
Supportive: Confuse Ray, Safeguard, Roar, Toxic, Rest, Heal Bell, Sleep Talk, Substitute, Curse, Dive
Offensively: Ice Shard, Body Slam, Ice Beam, Hydro Pump, Thunderbolt, Psychic, Frost Breath, Surf, Waterfall, Dragon Dance, Freeze Dry, Aqua Tail, Avalanche
**bolded are key moves
With these moves shown now let's try and think of abilities and stat spreads for a mega and this is what I am thinking...
Support Mega
Mega Lapras
Stats: 130/100/120/100/130/60
Ability: Regenerator
Bold 252hp, 200def, 40spdef, 16spatt
-Heal Bell
-Roar
-Freeze Dry/Surf
-Toxic
Outright this may not be the best set but in a tier where stall is a thing I would say this is an OK set. The choice of Freeze Dry or Surf is between getting walled by Grass and Water types or not being able to hit Fire types. In truth, if Lapras was capable of getting Scald it would be the other choice not Surf. Being an Ice type a (theoretical) Mega Lapras would still have a huge fighting weakness (and Fighting types run this tier in a sense). The Defensive bulk I think benefits a Mega Lapras more because specially you'd only have to worry about Electric attacks (since you can handle a Grass type) + Regenerator is an awesome defensive ability.
Offensive Mega
Special Mega Lapras
Stats: 130/110/100/110/95/90
Ability: Storm Drain
Modest 240hp, 252spd, 16hp
-Freeze Dry
-Surf
-Rest
-Sleep Talk
Unfortunately Lapras lacks Calm Mind or Agility, two moves it would greatly appreciate as a special sweeper. Freeze Dry is the optimal move followed by Surf for dual STAB. Rest/Talk covers any status changes you would need to worry about and its decent recovery. With all that said, having Storm Drain means you could easily switch in on hard Water types like Samurott, Feraligtr, Ludicolo, etc to get the +1 to spatt. (side note: Lapras has decent coverage moves like Psychic, Thunderbolt, and Signal Beam but without being in a better speed tier or having a boosting move it can't properly utilize them).
Physical Mega Lapras
Stats: 130/110/100/110/95/90
Ability: Water Absorb
Naughty/Naive 252att 252spd 4hp
-Dragon Dance
-Freeze Dry
-Waterfall
-Zen Headbutt/Body Slam
You may be asking why not carry Ice Shard? Well frankly speaking Lapras, on top of lacking Scald, decent recovery, and a special boosting move it also doesn't get Icicle Crash which would be the optimal move. Instead carry Freeze Dry with not only is STAB but allows you to not get walled by bulky Water types in the tier. Waterfall is your other STAB though if you are bold you can switch it for Aqua Tail at the risk of a 10% miss rate. The last slot is really up to you and how your team works. Zen Headbutt allows you to counterattack Fighting types if you manage to outspeed them after a DD. Body Slam is the decent neutral move choice with a chance of paralysis.
These are just a few things I've been thinking of today. Lapras does have a decent amount of options and I think it really does deserve a mega.
Because the point of this project is to keep the 'mon in NU standards, not making it to broken for the tier.Why not just have Mega Luxray be Electric/Dark with either Adaptability or Sheer Force. A boost to attack, speed, and maybe one of its defenses would do fine. Wild Charge and Crunch would be ridiculously powerful with Adaptability. Crunch and elemental fangs get Sheer Force boost.