A small 1-0-1 Kingdra line is an interesting idea, but the 10 extra damage isn't really that much of an issue in most cases. Most of the meta has an odd health (110, 130, 150) which Gothitelle is hitting on it's own without Kingdra. Only donphan (which there isn't much of in my area) has an even health (unless I'm not remembering somebody), and even then the Kingdra would just be used as an attacker against him for the x2 damage. Possibly better than the slowbro counter I mentioned in the OP, but I guess that would just take testing to decide.
I've been working with a 2-1-2 it adds a decent amount of pop to a Gothitelle, especially if you are going to play it with DCE for speed, in which case you do miss out on some key KO's. A DCE and a Psychic hits for 50, which puts most things in range for a devolving KO from Jirachi, and a benched Kingdra or two can make it hit that magic 60 or 70. I play the deck so that it abuses Catcher and then hits big with Jirachi later in the game, with Gothitelle taking out babies and Manaphys and other weaker Pokemon along the way.
Grumpig isn't that great imo, because #1, you are breaking the lock and #2 the damage output is flippy and not many people use poke-powers in the meta besides magnezone and typhlosion, but even then reshiram could take out a grumpig easy and magnezone's draw power down for one turn wouldn't cripple a deck that has been using it all game. Really though, breaking the lock is actually better for them because they can just spam all their trainers in one turn and could catcher up something that could in return cripple you. Spoink could be decent, but not worth the spots w/o an evolution and personally I don't see Grumpig even being as useful as Spoink.
For a 1-1 tech these two couldn't really hurt. I mean Spoink is a pretty cool card that gives you a 50% chance of locking them up at a key point in the game, which makes it worth the extra slot, and if you bring Grumpig along you can use it to attempt to swing for some real damage, Bench Manipulation may be flippy but with a full bench you can expect to hit 80-120 with it, which is decent for the deck, but you can also hope for more, and it isn't always a terrible idea to have a card that can come through in a pinch for you.
Obviously I was going to use the Jirachi/shaymin engine, just forgot to mention it in the OP. It is a flippy engine and not the most reliable, but it can get the job done for sure. Not enough to keep Gothitelle "swarming" as you put it, imho at least, but good enough to refuel a new Gothitelle if 1 goes down or get 1 powered up. The other option would be Jirachi/Mismagius, but I feel shaymin is much easier to use and more consistent than benching 2-3 Mismagius' just for the power.
If you drop the Shaymin to move the energy before the Gothitelle gets KO'd then it isn't impossible to keep it swarming. I don't actually like the idea of Jirachi and Shaymin being used to power this guy up at the start of the game, but later in the game these two make for a decent addition. But relying on 3 coin flips and two basics just to get some early energy in play seems to be too risky, I'd rather get a nice trainer lock and swing for my 50 with a DCE.
Whimisicott doesn't make much sense to me. It would require a tech of at least 2 grass or rainbow energies, neither of which are good in this deck, and the return is not worth it. And to make whimsicott the main attacker makes the deck horrible imo.
Whimsicott is garbage, but again an option if you want to play a rogue deck. It's the only thing we have that can boomerang, so it is worth a mention in a thread about techs for Gothitelle.
Magnezone would be a good back up attacker/draw engine with all the energy floating around on your field, for sure, but it feels bulky. Even a 2-1-2 line would be too much and, again, would require lightning or rainbow energy to function. And you are already nuking people with Gothitelle if you set it up properly so the idea of 150 a turn with Magnezone isn't really necessary. Personally, I don't see it being worth it but testing may prove it being successful.
If you don't play Kingdra I'd say play Magnezone, Gothitelle isn't a huge damage dealer, and with a couple of Jirachi and a Rainbow Energy or two Magnezone becomes a nice bulky way to effectively take down the Dragons, who are going to be a huge problem for a Gothitelle deck.
I thought about Weavile, but even with a 2-2 line you will still want to be seekering them to reuse them and the seekers would be better used on your Jirachi/shaymin engine to power something up. Maybe a 1-1 tech used in critical moments (like early game) but I can't see much of a use if you can only use it once or twice really.
If you are going for a Slowking and attempt a serious lock down, then a couple of Weavile to pick off their draw support is fairly important, plus having a couple more Pokemon with free retreat in a deck like this could be rather important.
Reuniclus seems too frail for this deck with only 90hp, even though it can't get catchered up, but if it proves it can survive then the dragons may be useful techs just to hit some weaknesses.
Well the #2 deck at worlds applied a similar strategy of locking trainers and then having Reuniclus moving the damage counters about for simple healing and better Outrages. This deck streamlines that strategy a bit, allows you to use Catcher, and the active has just as much HP as the dragons.
Also, the plan with Gothitelle (afaik) would be to abuse catcher yourself and knock out bench techs while crippling your opponents build and whittling away at their attacker's health, which you can also ohko fairly easily if you can set up fast. By itself Gothitelle can majorly screw with your opponent but it does seem like it needs something else to give it a better chance/edge besides simply locking up your opponent. With all this being said, I have very little hands-on experience with any lock decks so somebody with experience might be able to shed some light on this.
