You could try and use this card as a starter type Pokemon and use Oblivion Wing many times while setting up your benched Pokemon or you could set Yveltal up on the bench, put three energy cards on it and later in the game when you have plenty of energy cards in your discard pile you could move it into the active Pokemon spot and use Oblivion Wing to get those energy cards back, or you could use Darkness Blade to try and knock out your opponent's active Pokemon in one move
It exiles any creature for one mana
Coming back from the yard pushes Unstoppable Slasher over the top, though fun fact: If you put a -1/-1 counter or stun counter on it (or any counter, for that matter), then kill it, it wont come back
This can be your active Pokmon or a Pokmon on your bench
It can make its own mana rocks by simply tapping and paying three mana that will stay on the battlefield even if Svella ever leaves it
I made several decks using this feature, all of which managed to win me online matches