The best thing about Pokemon is that a huge percentage of almost every deck in standard consist of the same cards. If you buy that huge chunk, you can build just about any other deck you want by swapping out Pokemon, changing energy types and stadiums, and making a few tweaks to the trainer base. Those cards are:
4 Professor Sycamore
4 N
4 Guzma
2 Lillie
2 Acerola
2 Skyla
4 Ultra Ball
4 Max Elixir
4 Rare Candy
2 Rescue Stretcher
2 Field Blower
2 Switch and/or Escape Rope
1 Super Rod
2-4 Float Stone
3-4 Choice Band
2-4 Fighting Fury Belt
1 Oranguru
1 Sudowoodo
2-2 Remoraid/Octillery
2 Alolan Vulpix (with Beacon)
I'm probably forgetting something but I'm sure others can fill in the holes.
As far as Lapras goes, it depends on the build: speed, ala Speed Darkrai, or disruption, ala Quad Sylveon.
If you decide on the speed build, add 4 Aqua Patch to that list above, and consider some tech Pokes, like Wishiwashi, Glaceon EX, and Manaphy EX. Maybe even Alolan Ninetails (GX and non-GX).
If you're more into disruption, you'll require a lot of cards outside the norm, like Hammers, supporters that remove energy or deck out your opp, and stadiums that increase retreat cost etc.