How do you upgrade your characters to elites or even further, plus what..

To make characters elites you have to buy them over and over again until they get to elite 5 which is max. 5 is V and the plus is for either upgrading them to elites or upgrading their Special Moves....
Hope this helped

Just buy one special move and upgrade it to maximum.if you have unlocked all Special Moves then upgrade them all to max

This is how you upgrade a character to max elite rank. Let's say you have you're Bronze Nightwing. He is a lowly rank ZERO elite, meaning you have never upgraded him before. One day you decide you want to make good old bronze nightwing a little bit stronger, by increasing his elite rank you can do that. To increase the elite rank of mister bronze nightwing, go into the game shop and buy another bronze nightwing. After you have purchased your second copy of the lowly nightwing, a plus symbol should appear on the card in your collection menu. All you must do is click on nightwing, then click on the plus that says "promotion available" then your lowly nightwing will become rank 1 elite. You can repeat this process till the character is rank 5 elite. If you want to upgrade nightwings abilities, click on the card in the collection menu, then click on the ability that you would like to upgrade. It should bring up a tool tip on the abilities stats and a description of what the ability does, if you would like to upgrade the ability simply click buy.