If they can't attacksay because they get tapped before combat or there's a cost for them to attackthey just don't attack
naturally, the different cards and card types can add further, more complex abilities and effects to the game, but this is where it becomes incredibly addictive, as you discover new combos and favourite effects to use in your own decks
Chandra, Torch of Defiance will +1 to exile, cast, and then you can Shock your foes if you don't cast it, and then you can also just +1 her to make two red mana which can be used for anything
If youre looking for a great deck builder, try and track down copies of FFGs Netrunner
Mimikyu's value seems to hinge on the opposite: being incredibly terrifying and off-putting, but in an epic, menacing way akin to a villain from JoJo's Bizarre Adventure
Once you get the card draw started, you should have no problem funding Yuffie and your creatures' abilities