I'm El, I do Magic on the internet and you can find me on most forms of social media as defiantcathar doing charity work with Praetors for Change and streaming with PlayEDH
While its abilities and attacks arent incredible (though Pokemon Power: Step In provides a free Switch if necessary), its likely the novelty of it being Dragonites first appearance as well as the brilliantly colorful (and sweetly calming) artwork by Kagemaru Himeno that make this card an absolute classic, and easily the most valuable card from the Pokemon TCGs third set ever.
Pillar of War Pillar of War was playable in Theros Limited
Meaning that if you manage to pair this card with another card that limits attacks, your opponent will find themselves at the other end of a siege
The idea, according to Matt Tabak, is: The creature ducks out of action for a while and trains, and when it's big enough, you can go on the offensive. That means that the ability needs to be at sorcery speed flavor-wise