Time to get the achievement from start to finish: about 2 hours. You will most likely get beak lvl 99 at the same try.
You have to play chocobo hot n cold minigame for this. You can start it as soon as you get to Lindblum in cd1.1. You will find chocobo forest northeast of lindblum, where you'll get access to the minigame. Go there2. Start by talking to the kupo, and once you have the chocobo, go back to chocoforest. You can now play the minigame by speaking to Kupo again.
You have 60seconds to beak the ground. You will find all kinds of things, but what you want to find are chocographs.
Chocographs are treasure maps, where treasures are located in the world map.
There is a total of 24 chocographs. You will find first 6 in the chocobo forest.
Good thing is that the kupo will say when you've found all of them. If you are not sure that did he say it, you can go to world map with chocobo, press Y and see if you have the first 6.3. Get the first 6, then go to world map and start finding the actual treasures.
Check out IGN made a good walkthrough about it https://www.ign.com/wikis/final-fantasy-ix/Chocobo_Treasure_...
After the 4th chocograph treasure is found in the worldmap, you will get access to ride lightblue oceans in the world map.4. Now you need the hilda garde III to fly to that one island on the bottom left corner of world map. Then get chocobo to come to you on the trail of chocobo footprints and walk the lightblue waters to the chocolagoon.
Here you will find another 6 chocographs.
This part is easier as the lagoon is smaller.5. Afterwards go find the chocographs in the world map again. You will get the red chocobo from one of the chocographs.
6. Then go back to chocoforest, and get more chocographs. Now this is slightly harder as you have to jump on the platforms as well.
Always wait till the kupo sais that choco cant find more chocographs.7. Find more chocographs in world map again. Get dark blue choco.
8. Go back to lagoon, find more chocographs.
9. Go to worldmap to uncover the chocographs. Get yellow choco.
10. Then finally go to chocobo airpark.
You will access this with those dead peppers once you find a black spot in the world map. There are 5 of those and sometimes they don't appear, so if you can't find one, go to another spot in the world map.11. Now in the chocobo airpark find the rest of chocographs.
12. Go to world map once again and discover them. And after a total of 24 chocographs have been uncovered from the world map, you should get this achievement.
You should get also in the same time chocobeak to level 99 naturally. I got it till lvl 98 when I had all the chocographs, so took only 1 minute extra to get the final level.
This may seem tedious at first, but you quickly notice that you get the hang of it. Just have fast forward booster on.
Note: you need the chocograph before you can dig the treasure.