Let's talk F!sh

Generation Force is an exciting pack for sea-faring duelists. It introduces a number of Fish, Sea-Serpent and Aqua Monsters that creat an XYZ them as well as tons of spells and traps to support that. Sea decks already have tons of cards and awesome engines to boot. You have a:
Frog engine that puts monsters on your side of the field on each of your turns. With Fishborg Blaster you can make Formula Synchron and draw deeper into your deck than fish normally can. If you use Level Limit or Gravity Bind in your deck, your frogs will probably go untouched for a while.

Deep Sea Diva turns each of your normal summons into 2 monsters, a Diva and another Sea Serpent. You will mainly choose between Air Orca or Lost Blue Breaker, mostly depending on how your hand is and what your opponent has on the field. If you don't need a Diva to become a Smashing Ground or Space Typhoon, you can synchro 5 into Catastor or Gashilnodon. If you don't want to synchro summon, such as with Level Limit on the field, you can make a Gachi Gachi Gantetsu using 2 Divas. If you seem to have dead Divas on the field, you should consider using Genex Ally Birdman. As with any deck that Birdman is in, it recycles your cards and gets useless ones off of the field. Summon Diva, Special Summon LBB, Destroy their only s/t, then get Diva back with Birdman. Birdman can also attack under Level Limit and Gravity Bind.

Fish Stun is a rare treat, but Fish Stun plays similarly to Hero Beat. You have Fish Depth Charge that is a Gemini Spark for Fish monsters, then you just need good non-GENF fish to use it with. A few good examples of these are Fishborg Blaster, Golden Flying Fish, Oyster Meister and Nimble Sunfish. None of those cards are powerhouses on their own, and perhaps the best Fish to tribute for Depth Charges is GENF fish like Fly-Fang. You can use Surface on a lot of these monsters for awesome plays.

 Fly Fang - Inflicts Piercing Damage. When it inflicts damage to the opponent, banish it until your next Standby Phase.

It is too early to determine which build is the most powerful, as there is a lot of testing to be had. I took a moment today to build my own version of the deck, known as F!sh for now. It is in the pre-alpha stage, but I think I may have come up with a skeleton:
Monsters: 1x
2-3 Deep Sea Diva
1-2 Big Jaws
2-3 Fly Fang
2-3 Air Orca
1-2 Lost Blue Breaker
1-2 Wing Tortoise
1 Fishborg Blaster
1 Aqua Spirit
1 Sea Lancer
2 Mother Grizzly

Spells: 10+
1 Monster Reborn
1 Dark Hole
1 Giant Trunade
1-2 Mystical Space Typhoon
1 Level Limit Area B
0-1 Fish and Swaps
0-1 Fish and Kicks
2 Surfacing
2-3 Gold Sarcophagus

Traps: 7+
2 Solemn Warning
1 Mirror Force
1 Torrential Tribute
2-3 Oh F!sh!
1-2 Dimensional Prison

F!sh decks are not tier 1, let that be said now. I believe they fall along the lines of Nordics and Agent decks, where the cards themselves aren't the most powerful effects in the game, but they can make for very strong strategies. That strategy element is what I wanted to see out of this deck. The basic idea is that you have a lot of good cards that have fairly easy activation requirements: Oh F!sh, Depth Charge, Airorca and Surfacing. To make those cards live, we have other cards to make them available as soon as possible. Diva can summon Airorca straight out of your deck. This can turn Diva into a walking Smashing ground at the cost of removing 2 cards from your hand for 1 turn. As painful as that sounds, those removed cards will fuel something else, either this turn or next turn. You can perfom an XYZ summon with the Airorca on your next turn, or use it with Oh F!sh. Relying on Airorca to make Oh F!sh live was not enough, so I added in Gold Sarcophagus. Most of the time, I search out Diva with Gold Sarc. in this deck, 1 Gold Sarc makes Oh F!sh into a live card, negating any monster effect simply by shuffling the card back in. It is a bit like Divine Wrath, as you lose Gold Sarc and Oh F!sh to destroy one of your opponent's cards. Once again, doesn't sound game breaking, but when you combine it with everything else, it makes for very interesting gameplay.

Of course, besides playing with F!sh based trap cards, the other strategy of the deck is to perform XYZ summons and Synchro Summons. The easiest way to Overlay into something is to use a GENF monster to banish itself, such as attacking with Fly Fang. On your Following turn, you can put a level 3 monster onto the field to make a level 3 XYZ. F!sh have a number of ways to do this reliably. You can normal summon Diva to put a level 3 monster of your choice onto the field. With Surfacing or Salvage, that would be Lost Blue Breaker. With a level 3 GENF mosnter, your can Diva for LBB, and tribute it to destroy a spell or trap. Afterward, you can use any of your 2-3 Surface cards to bring LBB back and make a level 3 XYZ. If you put another monster into your RFP zone, your first XYZ can be Leviair. Using Leviair's effect, you can summon the banished F!sh monster and synchro with that lone Deep Sea Diva.

With any level 3 F!sh (Fly Fang, Wing Tortoise, etc) and 1 rfp monster: Normal Summon Diva, Special Summon a level 3 Sea-serpent. [If you have a Reborn-esque card in hand, get LBB. Use LBB's effect to destroy a s/t, then Surface to put it back on the field]. Overlay the 2 for Leviair the Sea Dragon. Use Leviair's effect to summon a banish monster from either player's side of the field. Finish by synchroing with Diva for Catastor, Lord Gishilnodon, Brionac or Gaia Knight.

There are so many cards you can use in this deck that it is difficult to choose between what is good and what isn't as good. The deck could even be made to control the duel with Dimensional Fissure and Macro Cosmos, 2 excellent Side Deck choices. In fact, with Gold Sarcophagus, F!sh can side into a very anti-meta side deck utilizing Necroface, Dimensional Fissure, and Fish and Swaps. Gold Sarc can immediately banish Glow-ups, Tengus and Gladiator Beasts from the top of the deck, leaving them with cards they will never be able to access. Fish and Swaps allows you to get banished monsters back to your hand in an even exchange(+/-0). If you do not like the idea of main decking Gravity Bind and Level Limit(there is no reason why you shouldn't), you can side them in against Gravekeepers and Hero Beat. It is especially useful to side out Oh F!sh against the latter and the rise of other beatdown decks(TGs) for generic cards. This would be Dimensional Prison if you don't already run it, or you can even run Zero Force, which will make all of their monsters 0 ATK when you banish cards.

If you haven't gotten a chance to test this deck out, either by proxy or online, give it a try. It does take a fair bit of skill, so don't dismiss it too quickly. Just try to come up with a strategy that is consistent and see how you can capitalize on it.

Here is my test version if you guys need some inspiration:
Monsters: 18
3 Deep Sea Diva (staple)
2 Big Jaws (Level 3 1800 beater.)
2 Fly Fang (Best F!sh in the deck imo)
2 Air Orca
2 Mother Grizzly (gets Fishborg or Sea Lancer)
2 Genex Ally Birdman (recycle Divas)
1 Lost Blue Breaker (easily searched out. 2 has been unnecessary so far)
1 Sea Lancer (Sub-par card. Not great, not bad either. Could be replaced)
1 Aqua Spirit (Utility)
1 Fishborg Blaster (Easy Synchros whenever necessary)

Spells: 12
3 Gold Sarcophagus (easy Divas and makes Oh F!sh live on turn 1)
2 Mystical Space Typhoon
2 Salvage (May up this to 3. Card is too good not to run in non-macro builds)
1 Monster Reborn
1 Giant Trunade
1 Dark Hole
1 Level Limit Area B (Many level 3 attackers in this deck. Also XYZ have no level, so they are unaffected)
1 Salvage (Get Diva or an emergency LBB)

Traps: 10
3 Oh F!sh (Too many game breaking effects in YGO to run less.)
2 Solemn Warning
2 Dimensional Prison
1 Mirror Force
1 Torrential Tribute
1 Gravity Bind

Extra: 15
1 Submersible Carrier Aero Shark
1 Gachi Gachi Gantetsu
1 Grenosaurus
1 Leviair the Sea Dragon
1 No. 17 Leviathan Dragon
2 Sea Dragon Lord Gishilnodon
1 Ally of Justice Catastor
1 Brionac, Dragon of the Ice Barrier
1 Gaia Knight, the Force of Earth
1 Black Rose Dragon
1 Stardust Dragon
1 Scrap Dragon
1 Colossal Fighter
1 Trishula, Dragon of the Ice Barrier (Mother Grizzly + Diva)

Side Deck: 15
3 Dimensional Fissure
2 Shadow-Imprisoning Mirror
2 Light-Imprisoning Mirror
2 Kinetic Soldier
2 System Down
2 Fish and Swaps
1 Maxx "C"
1 Necro Face