I agree with your feedback except for Mallow. IMO, the only argument against Mallow is that it's a dead card if Garbotoxin is in play and your field blower are nowhere to be found, but as long as you still have 4 Sycamore and 4 N, you aren't affecting your supporter-based draw power at all. On the note of the Garbotoxin, as long as you play Mallow first and grab a Field Blower in anticipation, you won't be locked out either. Just a thought.
Grabbing 2 guaranteed cards is actually sometimes a lot better than drawing for 7, especially mid to late game. If all you're missing is a Choice Band and a DCE then there you go. Take for example if you've already played 2 DCE and 2 Choice Band, and you know you have 1 prized. You're looking for a single DCE in maybe a 20 to 30 card deck. You would prefer to Mallow than Sycamore. Mallow needs good timing to be effective, but when it is effective it's much better than blind drawing for 7. The main issue I'm focused on is decking out though, really.
Let's say the average game is 8 turns long. You get 2 Zoroark GX in play on Turn 3 and begin drawing 4 cards every turn from Turn 3 thru Turn 8, which is 6 turns. That's grabbing you 24 cards from Zoroark GX's ability alone.
When you open the game for your hand of 7 and 6 prizes and draw for turn, you drop your deck size to 46 cards on the opening turn. Continuing from my scenario above, by turn 3 you will have a 44 card deck if you have played no supporters, never ultra balled to search out a Pokemon, or never played Lele to grab a supporter. We all know that isn't realistic, so let's say by turn 3 you have a 40 card deck without playing any Sycamore yet. If you draw 24 cards from Zoroark GX's ability, by turn 8 you are left with an 11 card deck, drawing 24 from Zoroark, and drawing 5 from each turn.
If you played 1 Professor Sycamore and ultra balled/lele'd multiple times throughout the game, then you've decked out.
Now let me take this back a notch. I'm not saying Professor Sycamore is useless. By God if you can draw for 7 to dig into your deck, especially early on, then go for it. You realistically won't be using Zoroark GX's ability twice per turn literally every turn. The point that I'm trying to make is that between Zoroark GX and Sycamore, you have enough draw power to deck yourself out very easily in 7 to 8 turns. Mallow lets you play efficiently by taking advantage of the draw power you already have instead of recklessly discarding a hand of resources to draw for 7.
2 Mallow is also justifiable for the draw rate. I ran 2 Mallow in my Gardevoir GX deck list and I never have to Lele for her for the right time. I did drop her to 1 copy in that deck though since Octillery is much less reliable than Zoroark GX for the ability.
I believe a 4/2 Sycamore/Mallow split is ideal in Zoroark GX heavy lists. You aren't too dependant on your ability by running 3 Mallow and clogging your deck, and you have Sycamore when you need it early to ditch bricked hands and get your momentum back. I personally see Professor Sycamore as being a very common discard target for Zoroark GX's ability in favor of Mallow for the mid to late game when the situation is correct, but you still run 4 to see it when you need it. Professor Sycamore is much more playable than Mallow, but Mallow is much more efficient.
