If I remember right you get the companion chocobo at lv 35 you can get the chocobo all the way up to rank 20 (rank 10 normally) to go past rank 10 you need Thavaranian Onion's at rank 20 you can max out all skill tree's for the companion chocobo so don't need to worry about the skills so much but if you do want to reset the chocobo at some point I suggest using the 250 Allied Seals rather than 48000 Grand Company seal's