Like most Pokmon cards, the value of Mew VMAX depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Fusion Strike)
Most ethical people would try to only play with actual cards, of course, but if it becomes truly impossible to tell them apart in a tournament setting, the lines will start to blur
That said, the Archetype is a lot more varied than just relying on that card
The level up frame never was used again outside this set
By being outside of the Standard format, MTG supplemental sets might include brand new cards designed specifically for a different format
It's easy to see why, because dragons are a well-stocked creature type in the game, and The Ur-Dragon's WUBRG identity means every format-legal Dragon is available to you, and they cost one mana less even when The Ur-Dragon is in the Command zone