Live/Evil Twin is where I want to start in the new meta. While Tearalaments might be a better medium term investment, both of the new Tier decks are also liable to be splashed as engines for years to come - they're simply too good at what they do. They're also liable to get limited or banned. This version of Spright isn't as dependent on Toad, so if Toad goes the same way it did in the OCG this version remains very strong. However, Toad makes Spright Elf much stronger, and I will run it while it is legal,
There are basically 2 engines in the deck - the Spright engine, which easily puts up negates but locks us out non link/rank/level 2s, and the Live Twin engine, which draws cards and pops/sends cards, but locks us into fiends. Having said that, there are combos that put up Trouble Sunny with lots of negates, and combos that are happy to just put up Ki-Sikil with Elf, Red, Toad, and Carrot. Cool, flexible combos. Evil Twins is also much better in this deck than in any other deck - Live Twins can actually summon the card quite easily, and it will help but the numbers on the board, and has occasionally helped break a board or two. Having Evil Twins and Sunny in the deck also means the deck actually puts up attack points really easily, and has great lines to OTK.
Into the card by card.
3 Starter, 3 Blue, 3 Jet. I don't think you NEED to play full numbers of all of these, but these are the Spright starters, and I think in TCG I'm gonna start on all 3 of each. Starter plays through Droll if you activate before the main phase, so this card gets much better in TCG where Droll is one of the cards you see more often in the absence of Maximum "C". Blue and Jet are fine. They're full combo by themselves, and 9 Spright starters makes sense to start at (though I could see myself going as low as 7). 2 Red, 1 Carrot, none of the bad one. I just don't want to run a bad honest even in pure Spright, tbh, but at least there it makes sense as a searchable 1 of. In the Twin build it makes significantly less sense, since you can OTK way more easily and aren't counting on always seeing a Spright. 2 Red makes a lot of sense to me, not only am I happy seeing Red, but I'd like to search a second on follow-up sometimes. 1 Carrot is... Fine? A spell/trap negate that pops is actually pretty good, it insulates us from Imperm, and it is always useful, but I don't think I need or want a second to ever show up. 2 Spright Smashers makes a lot of sense, it's an out for floodgates that is also good removal and searchable, and realistically I already like Cosmic Cyclone and Paleo Dinomiscus, this is just those but better in every way. If you're smart with this card it gets much stronger, but also 1-for-1 removal is solid.
I'm also FOR SURE running 2 Ultimate Slayer, with bricks in the extra. Sending Toad can be cool and useful in the deck, but really we're trying to hit a Link, Synchro, or Fusion and get a free 2-for-1. Dogmatika cards already really helped Evil Twin, and people have started maining Evil Twins in weird decks to run this card, whereas here it is totally free. So, yes, in the main. Realistically, if it isn't Spright or Tearalaments I'm not too worried about having a dead card anyways, except against Exosister, which is a bad matchup going second either way, and still a pretty good matchup going first. The rest of the format is screwed, and Slayer is still good against most of it. I give it less than a month before everyone and their dog is on 1 Evil Twins with some Slayer main, but in our deck Twins is also an Engine card, a tool for creating OTKS, and a tool for breaking boards. The card is better (in Twins) than I think non-Twin players recognize, but it really does help hit the numbers, and it has helped force out interruptions for me, and occasionally even broken boards.
For other Twin engine cards, I'm on 3 Live Lil-La, 2 Live Ki-Sikil, 1 Ki-Sikil Frost, 3 Sunny's Snitch, and 1 Password. Lil-La is preferred to Ki-Sikil because summoning Frost is access to a free draw 1. The engine locks you into Fiends out of the Extra Deck, while the Sprights lock you into 2s, so you have to choose between using Toad and Trouble - Trouble to break boards, Toad to stop them from making them. They also enable Spright plays by themselves though, and Frost even literally helps make Toad. 3 Snitch is great, theoretically it could win you on time, but the LP actually matter reasonably often given the archetype's generally low ATK points. We only run 1 Password because realistically it should almost never want to search out Evil Twins and is nearly always going to just be more copies of Snitch that lose to Droll.
We're on Toad and still want to full Spright combo with the Twins sometimes, so we've got the whole Frog engine. These numbers are pretty standard, not much to say. Seeing a Swap Frog is fine-to-great and you need enough Frogs to send. Dupe screws up the plan of beating over Sprights and Twins. Ronintoaden enables the Toad plays.
For hand traps, I'm on 7 with another brick - 3 Ash, 3 Gamma with a Driver, and the obligatory Called By. Ash wins over Imperm here by being generically good at stopping milling, wheras Gamma wins by protecting early plays like Starter and Snitch, as well as being a Level 2 that summons itself out to enable combos.
In the extra deck, I have some bricks for Slayer - Wind Peg and Omega as options vs Synchro Monsters, and N'tss to deal with Fusions. The deck also naturally wants to run Sunny and Toad, which are also great sends for Slayer. The goal here is to get a targeted 2-for-1 off of Slayer to very Specifically break Spright and Tearalaments boards.
2 of each Evil Twin is just about perfect. Because we're on Slayer, I'd consider a 3rd Trouble, 2 to grind and 1 to send, but I think these numbers are fine, enabling some grind game with the Twins, but also being able to put up a good turn 1 board whatever we're locked into. Toad is our best negate, and Elf lets us loop it in addition to being a great grindy card. Gigantic Spright enables Toad lines and can also help OTK, but even when you're locked into Fiends you can still make sweet plays with Red, Carrot, and Djinn Buster with Trouble.
The side deck is very targeted - let's fuck up the end boards of Spright and Tearalaments, with a little extra focus on ending backrow and outing the Mine, with a little extra respect paid towards Branded Fusion versions of Tear, on the basis of Anti-spell really messing with that deck, but also just being deadly going first against pretty much every generic deck floating around the meta.