Chocobo Sage's House - FF7 Walkthrough
You can reach the Chocobo Sage's house on Disc 2 anytime after you acquire the Highwind. It's found on the northern most continent between some mountains, if you're having trouble locating it I recommend you use my screenshot above that shows the map location.
At the Chocobo Sage's house the first and arguably most important thing you'll want to collect is the Enemy Skill Materia which is found by interacting with the Chocobo at the stable inside the building. It'll spit out the Enemy Skill Materia on the ground (as pictured below). Aside from the Enemy Skill Materia, you'll be able to purchase some greens and nuts that are useful in breeding Chocobos.
Chocobo Sage's Shop List:
Note: Purchase at least 50 Sylkis Greens from the Chocobo Sage when you have the Gil for it, we'll need them all for breeding Chocobos later.
If you don't have much cash and can't afford the 50 Sylkis Greens I recommend reading my how to easily get 1mil Gil without cheating guide. This is a method that should only take you an hour or two and it'll net you millions of Gil.