Deep Sea Diva Diva of the Dead 1380 She is running Diva Zombies, a deck-type capable of pushing out tons of Synchro monsters, so you'll want either anti-synchro support or anti-special summon support
Sugimoris signature, of course, adds a significant extra rarity and value to the card
If Gyarados's target survives the attack, Hyper Beam also forces the opponent to discard an energy from that Pokmon
Like most Pokmon cards, the value of Empoleon depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Platinum)
Bonker numbers for TCG Pocket Folks are commenting why POGO and Masters aren't on this, its because its going off of the "developer" lists for Apple and Google
If you prefer using a deck with Sapphire cards (check out our guide to Lorcana Ink Types for more details), it seems like a no-brainer to include Mufasa right now