So I started playing Duel Links today, and I've pulled an entire box of Gaia Genesis, because I initially wanted to play UAs. But there's also a ton of Mermail and Koa'ki Meiru cards in there.
Now, I don't know a lot about Duel Links and the meta here, but I've heard Koa'ki Meiru is really good. But at the same time, Mermail and UA seem like a lot of fun.
Which deck should I build? I want to be able to compete in the PVP, but at the same time, I don't want to waste too much money.
Post nerf Koaki is still decent, nowhere near it's full power but still pretty good against most matchups
Either of those decks could get to KOG.
1. Koaki deck will be hugely nerfed in the new ban list, so don't invest on it.
2. UA needs a way to bring Midfielder quickly. Cards like Sangan or even Field-Commander Rahz may help on that task, but still the deck bricks too much.
3. Other decks you can make with Gaia Genesis cards are Mermail and Aquaactress. But those two have lesser use in Ranked Duels nowadays
Mermail is also decent.
Since Cyber Style got corrected you don't see much U.A. anymore (can be bricky) however, U.A. penalty box can really ruin peoples day as well as the other cards.
I take a couple of Sangans to bring a Midfielder out as well as a couple of drowning mirror force if I need a turn's stall.
Koa'ki will be nerfed soon, so you shouldn't invest in that decks.
Full optimal UA is very expensive, but you still can try it with 1 Midfielder and some other tribute fodders you have.
If you want to build a powerful water deck with those Mermail/Atlantean Cards, invest in Abyss Encounters to get Sea Stealth Attack and Citadel Whale.