The Pokémon franchise of which they're part is one of the most successful intellectual properties in history, spawning countless shows, video games, toys and of course, its flagship trading cards featuring a host of cute and battle-ready creatures. No longer just a sign of schoolyard rep, the cards have become some of the most profitable assets in clients' portfolios, seeing more than 3,800% monthly cumulative return since 2004, The Wall Street Journal recently reported.