I’m with @KPiplup on this. 4 Squirtle is a staple in my deck because if I can’t draw into Squirtle, I sure as heck can’t get Blastoise out. I wish I had room for a 4th Blastoise but I haven’t had much issue with only running 3. I was debating trying to fit a spot in for Sacred Ash but I can’t find the right things to move. Perhaps it’s not even really worth it in the end.
Wartortle is vital against Item lock decks (Trevenant, Seismitoad). It helps you get the Blastoise out and running if and when you play against some of those item lock decks. 3 Lightning is my personal favorite because 4 is too much and 2 is too little. If this were a different meta and I could afford the space, I might consider running a more energy-centric line and dump tons of energy into the discard pile with Black Ballista. A big thing to remember is never have all of your energy on the field at once. If you have to Juniper away that 3rd (or 4th) Superior Energy Retrieval, your day is going to be pretty rough. I learned that after about 3 or 4 games of playtesting (online). I explained 1 Wartortle in the above paragraph.
I went 1-2 with this list at a League Challenge in Haines City a few days ago. The two losses were both to Seismitoad decks, but all three games I got turn 2 Blastoise and at the very earliest I got a turn 2 Black Ballista against my one win (a Plasma opponent). I still love this deck, but against Seismitoad, any stage 2 deck is going to have a pretty rough time, especially if you’re banking hard on that Rare Candy setup.