-add a buddy system.
like having them in the deck gives each other or allies a bonus of something. ex. mr hankey and stan. or garrison and mr. slave and/or mr hat. or terrance and phillip. ect

-distraction cards- they can be directed at all enemies or indvidual characters
ex. cartmans distraction card can be he that he cant do anything till he finishes singing come sail away (have sound clip)

another way is to play on your own cards
like put butters out and then play a local dmv card or whatever u call it and he can go to the nearest enemy and they must listen to his speech
or butters and his special sauce can do something

-an option to pick different arenas to fight in so you have a better chance of getting characters from that level that you dont have, i need inuit kenny.

-different battle options like co-op,
or king of the hill,
or first team to destroy something
or a time trial world challenge maps with leaderboards
or something else

-trap cards or this could just be a card but tom cruise in the closet is one of my fist thoughts,
place him on your side ande when an enemy comes near he can run out and do something

-player setup homebases, have random selector at begining of matches.
get cards like puddles, pits(potholes), the towers from campaign maps

-custom emotes, there are so many to choose from. maybe write your own, its not like there isnt swearing in the game

-last idea for now
Mitch Conner card.. play on any cartman and he becomes mitch conner and is on your team now

-other things ive seen posted in here that id like is
game recording and history
team/guild deck viewing
full donation count
upgrade item/card trading place
upgrade item donation
fix draw mode(rematch, highest health wins, ect)