As a free source of Bloontonium, this card helps if the player's deck relies on Bloontonium. It’s generally advised for decks that are going later to replace Bloontonium Cache with something like Haunting Night or Mine Supervisor due to their stronger Bloontonium generating abilities.
Heroes with more expensive abilities, such as Gwendolin will benefit from the Bloontonium fairly well if trying to get to the more expensive abilities. Be wary of actually getting to the higher Bloontonium costing abilities though, as one Cache is not enough to afford those more costly abilities.
Obyn’sWolves make Bloontonium Cache a better version of Dart Monkey for him, while also allowing Obyn to get Nature’s Shield up quicker. For faster Obyn decks, using Cache is often a good idea.
Mountain Obyn may rely on quick Bloontonium to start making Dire Wolves as soon as possible, in order to shut down grouped rushes. He can also use Cache to get more Sentinel Bloons or to use Brambles to survive in a pinch.