I weighed a few standard size Pokmon TCG cards of different types and rarities from the Crown Zenith set, and (based on this small sample), the more desirable holo and art cards do weigh more than a normal common card
Creatures (20) 2 Sheoldred, the Apocalypse 1 Faerie Mastermind 4 Deep-Cavern Bat 4 Preacher of the Schism 1 Vren, the Relentless 2 Azure Beastbinder 3 Enduring Curiosity 1 Floodpits Drowner 2 Cecil, Dark Knight Planeswalkers (1) Lands (25) Spells (14) The great one is back in Standard
Celebi V (Alternate Full Art 245/264): Has very nice, cutesy artwork and a high current market price
While there are other ways to level up, such as winning battles or using wonder picks, the most effective is opening packs
With the rise of Universes Beyond, its easier than ever to run that many legendary creatures in your deck