Most show up once in Standard, perhaps to be seen again in less restrictive sets like Commander, Battlebond, and Modern Horizons
You should also check out our lists of rare Pokmon cards and every Pokmon set in order.
Then I can check for overlaps of 2 (or if the rest of the sheet is nearly complete I sometimes only go with 1) and assemble the complete sequence
There's at least one Snickering Squirrel that would disagree
I am not fully up to date on the market for these cards so someone else may be able to help, but Id say if you wanted to sell the collection as is, assuming conditions are mixed, you may make $250 or so
Ive highlighted most of the usual suspects, and zombie Commander staples though theres plenty of overlap just in the combos listed here