On the subject of Thav onions to rank up your chocobo. It's been tested out today that it needs to be fed by you to actually raise the level cap of your chocobo.

Gave an onion to someone in the FC to feed it while I was a work after I logged in the morning to feed it, to reach capped exp, then take it out and kill 1 mob to reach the next rank.

So feed Onions yourselves!