Twilight Masquerade.

What Twilight Masquerade is worth today

The set carries $1k of tracked value across 226 priced cards, and Greninja ex accounts for 27.2% of it on its own. That concentration is the normal shape of a Pokemon set: a handful of chase cards hold almost all the money, 38 of them secret or illustration rares, and the median card sits at $0.32.

If you are pulling this set, the cards worth sleeving are the ones at the top of the list. Everything below the top twenty trades for less than the cost of shipping it, so bulk it and move on.