Its unfortunate that the mana doesnt stick around after combat, but you can sink it into activated abilities or instants
There are variety of ways to get rid of pesky opponent cards, too, whether it be more targeted like with Swords to Plowshares (a classic), Angel of Serenity and Angel of the Ruins , or a more Wrath of God-esque option like Cleansing Nova , Austere Command or the opportunistic Sunblast Angel
Both of these additions should help you churn through your deck to find the right spells you need quickly
Second, there's the Mega Evolution mechanic, where if you mega evolve a Pokemon, your turn automatically ends without giving you a chance to attack
A day later, The Pokmon Company pulled the design of a new Pokmon TCG Pocket trading card