They give special abilities and can be interacted with by certain character cards
You could pick off just one character with 2 Willpower, or ping damage onto two and finish them off with another character or ability
And if you want something on the wall, UV-protected frames exist for exactly that reason
Pikachu's second move is called Fly and it is pretty expensive for a weak Pokemon like Pikachu, it takes 3 colorless energy cards and only does 30 damage, and you have to flip a coin besides when you use this move, if it is tails the move does nothing but if it is heads all effects of an attack are diminished the next turn against Pikachu and that includes damage
This is sad news for bargain hunters, but the good news is that you'll still pick up plenty of free packs by playing
There's the advertised mode where the cast trigger spikes a few lands, then leaves you up a 5/8 and some extra mana on board