Gavi shows up in the flavor text of tons of cards in the main set of
Pokemon Card Strategy: So as far as strategy goes, since the main move you'll be using with this card is Power Whip and this move requires colorless energy cards you can use this Pokemon card in any type deck, I would recommend keeping Ferrothorn on the bench until you get at least 3 energy cards on it, you can then move it into the active Pokemon spot and use Power Whip and hopefully knock out some of your opponent's benched Pokemon
Variables that affect the market value of your cards Not really rarity but it falls under that sphere
The only requirement is a clear, reasonably high-resolution image, since print quality follows the quality of the file you upload
Honorable Mention #2: Wear // Tear If you like flexibility in a card, this is very useful
Your goal is clarity first , convenience second