The problem here is that your game sounds to be entirely based on chance with no strategy whatsoever. The gameplay boils down to this:
- build a deck consisting with the highest point valued cards you own, evenly spread between the elements.
- play games, win or lose by the hand of fate because you always select the highest card of the given element in your hand.
- buy new cards with the highest point values possible and replace the lowest in your deck.
That's it. That's the entire game. There is no strategy that is 'better' than the above. You're success depends only on luck, and a luck based CCG is doomed to failure.
My advice is to scrap the whole thing and start over. Play some other CCG games to get ideas on how to make great gameplay. In fact, here are some places to start:
Final Fantasy 8 and 9 had two simple CCG games that have many of the elements you mentioned.
The old Sim City CCG is a totally different kind of CCG and is great for coming up with new ideas in this space. All CCGs seem to want to mimic Magic the Gathering, and that makes sense because it is so popular, but there are many ways to skin this cat. Find a better one.
Have players play cards on a grid, first to a spot gets it, once each player lays a card on the grid, they all flip, and the next turn begins. This minimizes the time players spend waiting and encourages them to act fast to be able to plan their next move and to get the best spots. The backs of the cards might indicate only what, about the card, allowed it to be placed legally. Or it could indicate nothing and because it is digital it resolves the problem a game like this would have in reality, human error.
Free Game Idea
Cards are square and are lined on the edges with up to 3 elements, better cards have more element icons along more edges, each edge has at least 1 element. A card can have 3 fires on one side or 1 fire, 1 ice, and 1 water; for example.
Cards are placed on a N X N grid (where N is the number of players times 2) in any location, upside down.
Once all the cards are laid, they flip and follow these rules:
Fire beats Ice beats Water beats Fire (add more elements if you wish) However 2 Fire stalemate with 1 Water and 3 Fire beats 1 Water. Cards have ownership that starts with who places them, if a card is beaten by a play, that card becomes owned by the owner of the winning card. When a card changes ownership, any cards next to that card that have not yet been flipped this turn due to being beaten are ALSO beaten and flipped, creating strategic chaining potentials.
Stalemates don't cause ownership changes if two cards have JUST been placed and flipped, but as parts of chains they act as wins. Think of this as all cards gaining 1 of each element if they have just been flipped, by any means.
Once all the slots are filled and flipped, the player with the most cards owned by them on the board wins.
This enables weak cards to still be of strategic value, when played correctly on the board.
In this model there are no unbeatable cards. 3 fires can be beat by 3 waters, cards with 1,1,1 are great for creating chains.