>>47694473It's definitely one of the rarest and most prestigious ribbons available, probably second only to the National Ribbon since that one is limited to Shadow Pokémon.
>>47694483His responses are based on the Pokémon's happiness, and he gives it the Footprint Ribbon if the Pokémon's happiness is maxed out. But from Gen 6 and onwards, it was changed so that he checks how many levels your Pokémon has gained since it joined you, and it needs to have grown at least 30 levels to get the Footprint Ribbon. It's actually a very appropriate ribbon to bring up when talking about "stories and legacy" because that's the whole idea with it, that you and your Pokémon have come a long way together, having left many footprints behind in your journey.