This is a hidden rating system based on the Glick Rating system which is similar to what is used in chess for rating player strength
Like most Pokmon cards, the value of Charizard-GX 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 (Hidden Fates Shiny Vault)
Two mana to tap a permanent and draw a card isnt the worst because you can deal 2 damage to an opponent as an alternative
Artifacts are colorless most of the time, which means they don't need to be summoned by a particular mana type
And if that fails, then you can use your other grass Pokmon like Paras and Parasect who have high-damage attacks but do require a lot of energy
This doesnt mean you cant put legendary creatures like Jazal Goldmane at the helm of a token deck in Commander you can and your deck will likely see some success through always having a way to close the game