OOOO I haven't edited my deck since GRI, this new card from BUS will do Aegislash good!
I've had a game wherein Aegislash KO 3 Pokemon-EX/GX (a Volcanion deck) and land me 6 prizes in 1 turn, lol. Of course there was a lot of stalling involved, some weird Guzma/Lysandre + Bursting Balloon combos that must've led my opponent confused on wtf I was trying to do. Once 2 or more of their Pokémon had 100 or more damage, I used Ninjaboy to get my Honedge from the deck and Rare Candy'd my way to use Painful Sword!!
6 prizes won in 1 turn!!
That said, Aegislash is pretty slow to setup and best used late-game, preferably with stealth on your side... And Ninjaboy is one of the best, underrated cards in the game.
BKP Espeon-EX is an invaluable asset to the Aegislash deck. If Painful Sword didn't get to do as much damage as intended, or if you didn't get to setup Aegislash at all, Espeon-EX's Miracle Shine works wonders to help KO your opponent's Pokémon - well, those that can/have Evolve(d) anyway. In my experience, Espeon-EX gets the chance to KO Pokémon much more frequently than Aegislash can.