What in-game hints are given for the evolution of Feebas?

Feebas evolves into Milotic either by significantly increasing its 'beauty' stat or by trading it while holding a Prism Scale. Both of these triggers for evolution, as far as I know, are unique to Feebas.

A friend of mine has recently started playing Pokemon, starting with Ruby, and aims to fill the Pokedex as much as possible without any outside advice. He was lucky enough to backtrack and find Feebas with little effort but is not using it in his main team.

From my own recollection of Gen. 3, there were never any in-game hints as to how to evolve Feebas. I either found out by looking at a guide or being told by someone else. Is my own recollection of Ruby, Sapphire and Emerald incomplete, or were there really no hints given in the games on how to get Milotic?

Solution 1:

Most evolution requirements aren't revealed in-game.

I have played through Gen 3 many times, it being the first pokemon game I had and it also working on an emulator on my laptop.

In regards to the beauty stat, it is never mentioned in game as to the requirements for evolution, and Prism scale wasnt introduced until Gen 5 (as there wasn't a 'beauty' stat to raise in that Gen).