They evaluate cards in a three-step process that consists of authentication, grading, and encapsulation, and their site lists the exact parameters for each number on the grading scale
For example, you can put a Charmeleon card on Charmander, then later Charizard on Charmeleon
Kalamax, the Stormsire Free copies are good
That means you are doing more of the work: getting the images, formatting fronts and backs, and pushing everything through a card designer tool that is not MTG-aware
Its a fun challenge to get someone to recall the modes on a Player Rewards Cryptic Command, but when facing down multiple minimal-effort proxies across a table, it can become frustrating quickly if those proxies arent providing an accurate level of detail to represent the card they are meant to be representing