Given how cheap the initial cost is and the big impact it has, leveling up this enchantment doesn't need to be a priority, but if you have a few creatures on the battlefield and want to let your hand build back up, you can focus on pumping mana into upgrades
Measuring card quality gets considerably more complicated once you go beyond these simple examples, but the basic idea that higher quality cards generally make it easier to win games is all thats really needed to highlight what actually makes these 1 mana tutors so powerful
The 'Best' version is made of cards from all four Lorcana sets, including legendaries
Not only is it difficult to determine which cards are good enough, there has to be enough other cards that also pair well with them in order to make a wedge viable in the Standard metagame
This, of course, includes Pokmon cards
Itll tickle some players' fancy, and is admittedly quite powerful, especially with flicker effects to make more Robots