(If this creature isn't monstrous, put four +1/+1 counters on it and it becomes monstrous.) P/T Set Number 91 Language Espaol Legal Formats Commander, Legacy, Vintage Not Legal Formats Alchemy, Brawl, Competitive Brawl, Historic, Modern, Pauper, Pioneer, Standard, Timeless Rulings (3/8/2024) Once a creature becomes monstrous, it can't become monstrous again
You can see this at your local game store or from your favorite streamers
However, what we can do is look at heavily played Standard cards, and see when (or even if) their impending rotation caused people to sell on a card
To find the current market price of a Pokemon card, your best bet is to go to ebay and search sold listings (not "for sale" listings): Go to ebay
It is a huge payoff card for being mono white with its high stand alone power level
Since this is a dual ink card, your deck needs both Sapphire and Steel to make her work