On top of the above skill traits, we've come up with multiple ways for you to unlock and/or evolve into new cards in the middle of fights instead of only outside of them. Note that evolution and/or morphing can only occur once a day, and counts toward the maximum amount of traits you can use in a fight. Mechanics subject to edits.
Card Evolution
(http://img2.wikia.nocookie.net/__cb20130112011316/cardfight/images/e/e9/Dragonic_Kaiser_Vermillion_%28Full_Art%29.jpg) -> (http://img2.wikia.nocookie.net/__cb20130826044245/cardfight/images/9/94/Dragonic_Kaiser_Vermillion_THE_BLOOD_%28Full_Art%29.jpg)
Aside from necessary development required for Crossrides, it's sort of lame you would only get them through randomly appearing in your hand on the fields, or getting them as a gift, right? Yes it is, so let's do this like Yugioh. In there, cards are suddenly in the deck/extra deck at the moment the protagonist makes up the evolution requirements. On a game simulator I use, we have side decks to put in cards to develop into at the right time. CFA doesn't have that, so we're going to improvise by using G Units. To proxy your desired evolution, you can use a G Unit from your Generation Zone, and drop its power appropriately. You will have to remove a Grade 3 unit from the game from your hand. It'll be a chore seeing as you'll have to keep putting the G Unit back and adjusting its power, but it works. After that, you no longer need to use the G Unit, just put the actual card in your deck!
Card Morphing
(http://img1.wikia.nocookie.net/__cb20150307234549/yugioh/images/c/cd/RankUpMagicLimitedBariansForce-JP-Anime-ZX.gif)
Ah yes, I'm sure everyone remembers the moment Yuma literally broke the game by changing a card's everything because plot. Well, good news, we can do the same. This one is really simple. Put the new card that the previous will be morphing into in your deck, and play normally. Whenever the card shows up, treat it as the original (adjusting power accordingly), then roleplay magical things to change the card into what it really is.