All 3 teams are running on the same basic premise: let Pilo be your Electric counter so you can get a little more adventurous with the Lax set. The rest of each team then revolves around Spikes support, in part because teams were also hamstrung by having to use Skarmory, which is associated with stallier builds.
Eeveeto's team has a couple of big issues. It wants to abuse Spikes real bad, but has no way to keep them against a Starmie. Toxic > Sludge Bomb may be better on Qwilfish so you don't run out of PP trying to poison the bugger. Without Spikes, most of the team can't generate any offense, which is particularly bad when you're running Egg - he's a transient fellow, and with a team that moves this slow, he tends to just die or be dead weight. The only thing capable of offense outside of Spikes is the Drumlax, but without Pursuit support it's hard to see how it doesn't just get hardwalled by a Jhost. Simply put, it's hard to see this team working on a consistent basis, at least not at the highest level of play. Spikes-abusing teammates without a good way to keep Spikes on Starmie, and a weird Drumlax set left out on an island. They're two concepts that just don't have enough support and don't seem to mesh very well together.
Zokuru's team I think is more solid. It leans harder into the Spikes angle, using Toxic Lax (which has more natural synergy with Spikes than a lone Drumlax) and a spinblocker. One complaint is that this team is just a modified standard team: consider the team with Raikou / Skarmory / Cloyster / Misdreavus / Miltank / Snorlax. Put Zapdos > Raikou and Piloswine > Miltank and you get Zokuru's team. I know hands were tied with Pilo, but Miltank is the standard way to make your Cloy last longer by allowing you to cleanse its Poison, so replacing it so that you can run Zapdos > Raikou is dubious and probably makes the team worse. However, I will say Zokuru has good ideas to mitigate the downsides of this substitution, including the use of HP Elec Cloy to try to nab the surprise kill and ST Misdreavus to help it tank more Starmie Surfs now that Cloyster can't nail it with Toxic to put it on a clock. Apart from that complication, there's my personal distaste with Toxic Lax arising from the fact that teams that use it (including this one) seem to lean on it pretty hard, which renders them shut down by off-beat but not-impossible things like Rest Tyranitar or (as is used in this team) Rest Misdreavus.
Century Express's Spikes concept is solid, too. Rather than a spinblocker, they use Umbreon to Pursuit the problems away. It can chip at Cloysters and eat up all of Starmie's Recover PP (Umbreon vs. Starmie is actually a really complicated matchup: At first glance, Umbreon traps it; on second glance, Starmie doesn't have to switch out, it can just PP stall Umb; on third glance Umb can waste a lot of PP and is perfectly happy with wasting Recover PP or perhaps even enough Rapid Spin PP that Spikes is left with more remaining PP). HP Fire Forry covers opposing Forretress. I've toyed with this setup myself for the Spikes game, but my distaste for slow burns led me to look elsewhere (it's basically a setup that explicitly looks to grind out a win over the course of 300+ turns; at least there's also Drumlax on this team to maybe end the game in a more timely manner). Plus, there's one fellow that it absolutely cannot handle: Rapid Spin Tentacruel. Admittedly, it's quite nonstandard, but it's less of a non-factor than you might think, and if you see one, your slow burn goes right out the window. In addition, I'll disclose that I find Umbreon's "support" (as opposed to "trapping") sets dubious. One reason I feel that way is on display with this team: you can't reliably Pursuit Misdreavus, as you don't do enough damage and it just kills with Ptrap. So the LK Drumlax waiting in the wings as the alternative win condition (as opposed to "win the spikes war and wait until you can infinitely switch and your opponent can't") is liable to be walled by a Jhost even with the "Pursuit" box checked off.
Overall, my vote goes to Century Express. Eeveeto's team seems a little too flawed. Zokuru's team is a little too close to "The" standard GSC team (not that CE's is a revolutionary concept, but it's certainly a more uncommonly seen idea). CE's setup also requires more specific pieces to shut down: Both Tentacruel with Rapid Spin and a Ghost-type with Rest or Perish Trap. Zokuru's team, on the other hand, withers and dies against a lone Rest Tyranitar.
For fun, I might personally have gone with a setup like this:
Piloswine - earthquake / ice beam / toxic / rest
Skarmory - drill peck / whirlwind / rest / curse
Cloyster - surf / toxic / spikes / (rapid spin | explosion)
Snorlax - double-edge / curse / lovely kiss / rest
Zapdos - thunder / hidden power water / rest / sleep talk
Tyranitar - rock slide / crunch / pursuit / flamethrower
I normally use Nidoking > Pilo here, but Piloswine is much more reliable against Electrics, covers my butt against Gengar a little better too, and still has some of that mixed attacker flair (though it needs to try to freeze Skarm if it wants to beat it by itself; that or run Blizzard, but that's probably ill-advised as it's the easiest PP stall Skarmory has ever had to face. I mean what's Pilo Blizzard against Snorlax Fire Blasts or even Tentacruel Hydro Pumps?). Toxic on Pilo helps me nail Cloysters trying to switch into it, all in an attempt to have my own Cloyster last the longest.
Skarm is just good Snorlax insurance. It isn't complicated, doesn't really contribute to team synergy, it just keeps things from getting out of hand against public enemy #1. And that's good enough. It also covers Egg and Marowak which is quite a big deal.
Cloyster lays Spikes and spins them. Its only support is Ttar, so Spikes are far from guaranteed, but with Ghost removal, Rapid Spin, Toxic on both this and Pilo to wear away at opposing Cloyster, and STAB Surf & Ttar Flamethrower + Pursuit to wear away at Forry, plus Cloyster's own Spikes in the event they don't even have a Spinner, my aim is not to keep Spikes per se but rather to at least tie the spikes war (i.e., we both either have spikes or don't, no one-sided affairs where my opponent has all the fun). That said, Explosion is a serious option as otherwise Snorlax loves to come in and set up on this, as does Vaporeon. Not much point playing for the long-term Spikes game when one of those two is getting beefy in the here-and-now. Plus, Explosion can trade with Suicune or Vap or Umbreon if the opponent has it; they may be more than happy to throw them in Cloyster's face to avoid losing their Zapdos to an errant Explosion, particularly if it's the early game and I haven't revealed most of this team. As it turns out, this team really loves not having to deal with Vap / Cune / Umb, as having them around makes the lives of Ttar and Piloswine much more difficult. Full disclosure though: Suicune is a dangerous click, as it outspeeds everything but Zapdos on this team, and survives Explosion relatively handily - it's guaranteed to have enough HP after Leftovers to switch into Spikes once if it eats Explosion at full health.
LK Curselax can be super dangerous for teams with only 1 Normal resist, and if they have 2, I can use Pursuit to try to keep Spikes so Zapper has an easier time killing Snorlax, or I can use Pursuit to try to take out that other Normal resist, or I could try to use Pilo's mixed attacking prowess & freeze chance to create opportunities (if it freezes Skarm while a Ttar is LK'd, or freezes a Miltank while Skarm sleeps, LK Curselax can go to town). LK Curselax also functions as emergency defense, particularly against Fire laxen. AA Vap could also be a problem if Zapper somehow leaves this mortal coil, so LK Lax can at least make its life complicated in that scenario. If LK is used defensively, however, I admit there's a lot lost in terms of my ability to break through with Lax.
Zapper runs HP Water to mitigate a slight weakness to Rhydon; with Skarm + Ttar, being able to hit Egg is less important anyway. Apart from that, it covers key threats like Vaporeon and Machamp and just functions as good ol' sleep talking / status absorbing / thunder spamming Zapdos, functioning as defensive glue while also potentially creating opportunities with Thunder para or even the errant Thunder crit.
Mixed Ttar is a great way to get the most out of Pursuit; one of its biggest uses is getting Jhosts out of Snorlax's way, but it also pressures Forretress, Miltank, Skarmory, Exeggutor, and even low-health Snorlax. Hell, if I'm in a hole, I can even play for long sleeps against LK'd Rhydon or Steelix, or play to Pursuit Cloysters and Starmies. Ttar is the keystone to this team; without his potential to create opportunities against a variety of foes, everything else just sort of falls flat. It does mean I have to play him carefully to avoid getting Toxic'd, however, which is a pain.