Its a bit counterintuitive to think that adding even more cards to the deck is going to make you draw your bombs even more, but cards like Foresee and Ponder really do fight against the dilution of the deck
No matter how obscene it is, how skilled you were with it was often the difference between drawing six cards and drawing ten, or the difference between a kill and an empty board with an overflowing hand
Yes, Mega Gengar EX is one of the top chase cards and is worth pulling in Pokemon TCG Pocket
However, you can use them to fuel the abilities of your permanents on the board, so they can be a powerful source of mana
Its the ideal card to sacrifice or discard, but the surveil effect means its also just fine to cast when you need to commit to the board
Sacrifice after III.) I Until your next turn, each creature attacks each combat if able and attacks a player other than you if able