Can I create an online version of a card game? Just for experimenting. Is there any possible legal implication? In this case the card game is called Rick and Morty: Total Rickall.
Sort of. Maybe.
What you definitely can't do is to use the name "Rick and Morty", any art from the game or anything else which is covered by copyright, trade marks or any other form of intellectual property which is owned by anyone other than you.
However, it is probable that game mechanics themselves cannot be copyrighted, so you may be able to create a game which has exactly the same mechanics as Rick and Morty: Total Rickall, but with your own art, your own name, etc. However, if this becomes at all popular, I'd still expect the publishers of the game and/or the Rick and Morty rights holders to make your life difficult. You might win in court, but it's probably not worth the fight.