about low IV with best moveset

Yes! Lapras' base stats are already very good even before IVs are added. They are

Attack: 186
Defense: 190
Stamina: 260

And the way IVs work is really simple, the IVs are just added onto the base stats, so if your Lapras' IV for stamina were a 6, for example, you'd add that onto Lapras' base stat for stamina, 260, and the stamina of your particular Lapras would become 266.

If you click on any Pokemon in the Pokemon list on this site/app and compare their base stats with Lapras', you can see that even a Lapras with 0% IVs is still stronger than all but a few of them.

Lapras is always great but this one don't power it up too low IV almost 200 cp less.

For attacking, moveset is priority over IV. Knowing how to dodge makes a bigger difference than having nice IVs. Once you have enough monsters with the same A-grade moveset, and you run out of stardust, you can then look at IV to decide which to power up. For defending, IV is priority if you want top spot, and this only applies to dragonite.