Stellar Crown.

What Stellar Crown is worth today

The set carries $627 of tracked value across 175 priced cards, and Squirtle accounts for 18.8% 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, 22 of them secret or illustration rares, and the median card sits at $0.27.

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.