Forum Thread

1. Your coin and the one next to it look so similar! (Slightly increased breeding chance) - This message strikes me as comical since you would expect 100 Pokedollar coins to look alike. However, this could possibly indicate that when you tossed in the coin, the water created an illusion, and when you looked to try and spot your coin, you got confused by yours and the one next to it.
2. Your coin is shining bright in the water! (Slightly increased shiny chance) This message is fairly simple, your coin shines bright in the water. That's it.
3. Your coin is shining much brighter than all the other coins! (Increased shiny chance) Same as above, with maybe the exception that your 100 Pokedollar coin was fairly new.
4. Your coin looks much larger than the all others! (Increased mega-able chance) This message can also be explained by Snell's Law of Refraction, which explains why objects may seem bigger underwater than in real life.
5. Where did it go? (Nothing happened) There are too many coins in the fountain!
6. Your lucky number today is __ (Nothing happened) Maybe you decided to count how many coins are in the fountain, or some other random object. Still, this leads to a question: What if the number really is lucky? Is it how many eggs in your chain for your shiny to hatch, how many interactions to make, etc.
7. Have a great day! (Nothing happened) A nice passerby wished you a great day! Unless the fountain is sentient....
8.Did you know that coins from the fountain are donated to charity on a regular basis? You have done a good deed! (Nothing happened) You met the person who gathers up the coins from the fountain!

It is important to mention that you can also throw money into the fountain in Cerulean City and Vermillion City in other Pokemon games. But we are not here to talk about that. When looking at the fountain from the Town page, you can see three ornaments that may seem a bit unique. A yellow crystal, two Luvdisc, and two Alomomola. The yellow crystal does partially resemble a Griseous Orb which is used to start the Giratina Quest in the Ancient Cave, but it is more likely that it is just a decoration and the same for the Luvdisc. The Alomomola, are another thing.
If you look at the official Alomomola Dex entry, it says, "Fishermen take them along on long voyages, because if you have an Alomomola with you, there’ll be no need for a doctor or medicine.". And if you look at the Pokeheroes Dex entry, you get, "The special membrane enveloping Alomomola has the ability to heal wounds." From these dex entries, you can tell that the Alomomola have some type of healing power. Now from the dex entries we can derive that alomomola could cure/heal most common ailments and injuries. However, something else is at play at the fountain.
Whoever built the fountain was able to do one of two things:
(A) Harness the essence of the Alomomola and increase its potency to other regions, or
(B) Capture two Alomomola and genetically modify them to have their powers increased, and they reside in the fountain.
Whatever the option, the healing powers of the Alomomola/the Alomomola essence went from simply healing ailments and injuries, to changing the genetic code of pokemon (to make them shiny), or strengthening their growth and reproduction rates. All of it naturally, without contact, and temporarily. Best of all, the Pokemon comes out unharmed by the next day!

First thing to look at about this pokemon is one of the lines in the event announcement (which can be found by scrolling down on the News Page) which says, "A group of Hippopotas loves it so much that they even mutated into a special Water-typed species over time!" This tells us that the sand-loving Hippopotas somehow came to love hanging out by the water-filled fountain. There is no sand in the area if you look at the Town Art. Now, I think that the term mutated may be incorrect. Instead, I think that the Hippopotas evolved into the Hippopotain over time. Some of the changes that happened during evolution involved a stone-styled camouflage and the ability to store and expel water. Otherwise, they grant no special effects; they just live there!