Versión en Español: viewtopic.php?f=19&t=11409&p=53551#p53550
My deepless thanks to: Selomytha, Deitas and camckee316. (If I forgot one, comment below please!!)
Let's get to it.
Full map: http://i.imgur.com/dYlAaGQ.jpg
-Start the event by talking with the NPC near the logs on Easterbourne Farmlands. (Picture provided by Staff, click here)
-You will need a seviper enabled for quest and off from your team.
Seviper: Press x behind the tree on route 5: https://imgur.com/a/jMVln. You can also find it at route 7 but is rare pokemon.
-Go back to the event place and show the pokemon to the NPC.
-Catch a Bouffalant for the old Man, enable it for quest and remove it from team. (Don't worry, you will keep your pokemon)
-Now you will have to gather some materials to repair the fence.
-Go to Eastbourne City and talk to one of the construction workers, mention that Jimmy sent you.
-Go back to the Old man.
-Talk to hes Granddaughter (Girl in blue).
-Accept the deal and go to Easbourne Shore and talk to the girl. (I choosed the option ''talk to the magikarps'')
Make happy the Magikarps: https://imgur.com/a/yON4g
1st Magikarp: Talk to it and it will be happier.
2nd Magikarp: Is already happy. You need to have at least an ultraball and 1000c
3rd Magikarp: Bring 10 rock presents. (Rock present are dropped by zubats at the cave on Route one, Full map found at the top)
4th Magikarp: Magikap LVL 200 will battle you, defeat it.
5th Magikarp: Magikap wants to see the other magikarps happy. When all the Magikarps are happy, you can interact with this magikarp to travel to Magikarp isle.
Now a shot cut-scene starts: PLease read what the NPC says
-Let's enter Sara's house and talk to Sara.
-Follow Sara to the south side of the Isle.
-Kick hoolingan's butt out of Magikarp Island! We want that egg
Hooligan do have: Bouffalant, Tauros, Gyarados, Beedrill and Cinccino LVL 100.
-Enter the southern house and interact with the hooligan.
-Go back to the rach with the Tauros and capture 8 ponytas, enable them for quest and take them off your team.
-Talk to Keri's brother (Read haired NPC) and give him the Ponytas.
-Go back to the Magikarp Island and interact with the egg.
-Talk to Keri.
-Defeat larvestas for ''Solar drops''. Collect 30 of them.
-Go back to Tauro's ranch and talk to the Blue Haired NPC found to the north and give him the Solar drops.
-Use the Pick lock on the Pokeball found in the southern house at the Magikarp Island. Boom! Not going to spoil! ConGratz! It is the only 1 you can get! Good luck!!
-Defeat kakunas and metapos to get ''Fall Pebble'', Go inside the southern house and talk to the NPC with Pink clothes and exchange the Fall Pebbles for Glowing Bait... Use 15 Glowing bait on the egg at the southern side of the isle to get Tirtouga: there is not ''Females in this event, but a new egg will respawn every 24 hours. Good Luck!
-Now let us go to the southern-west NPC and give him Glowing baits... you may fail a few times, but do not worry, Basculin will appear soon or later! Defeat it and it will join your team.
-Go inside the Southern house and interact with the Magikarp poster (Click here). Bring the pokemons:
Beedrill-Butterfree-Gyarados; Enable them for quest and remember to take them of your gallery and team.
-Now we should go outside to the west and we will see Mew at the water well: It teaches Fly moves.
Finish.... hmmmm... ZZzzz... Pay 8mill to the Pink-haired girl on the Island... and Who knows '-')7
Non-Map pokemons able to get!
Bouffalant: Catch it at tauro's ranch|Rare.
Cottonee: Appears everywhere at Magikarp Island|Uncommon.
Larvesta: Appears everywhere at Magikarp Island|Rare.
Basculin: Give ''Glowing Bait'' to the fisher and if you are lucky you will encounter it, Defeat and it will join.
Tirtouga: Use 15 Glowing Bait on the Egg on the ground: You can do this every 24 hours. (100% male)
Axew: Use Pick lock on the Pokeball inside Southern house.
Audino: Appears everywhere at Magikarp Island|Rare.
What to do now??
1.-As usually, you can shiny hunt non-maps.
2.- You can feed your daily egg for a male Tirouga
3.- You can defeat larvestas and when it is night you can go to the pond to change them for rebirth crystals.
4.- Inside the southern house on the Island, the northern-west NPC will give you Eevee candies, coins, pokeballs and more. (all by random luck)
5.- Same house you also get glowing bait for more tirtouga or Basculins.
6.- The old man's wife at the ranch will give you: 1st day dinner coupon, 2 day pp max, 4 day everstone, 6 day minccino
I do rally appreciate you read my guide and I hope you guys liked it! Good luck every! Have a sweet after summer event!!