"To solve this quest as efficiently as possible, use the following pairs:
Greedy and Indulgent
Dainty and Adamant
Naughty and Considerate
Gourmet and Excitable
Naughty and Brawny
Thanks to commenter Xereseo for this!
Original
This is considered a quest event in Colony Mu, but it doesn't have an actual quest name associated with it.
I have to be honest, I don't really understand how this breeding minigame works. I was able to clear it, but I couldn't tell you how specifically to do so.
From what I can tell, raising Armus comes in three stages, where you have to give Tussore items to feed them for each stage. After that, you'll have to pick a pairing to breed. Then after it rains, you'll get some items. Most of the time, you revert to stage 1 and have to start the process over, but eventually you'll be able to clear the quest vent.
For the three stages of feeding Arduns/Armus, I believe these are the best foods to use, based on availability.
1st stage: Pulpgrass gives 25%, you can buy in Colony Tau
2nd stage: Cracker Nut gives you 20%, can buy in Colony 9
3rd stage: I believe you can only buy the 2% items here, which sucks
Dish Philodendron, buy in Castle Agnus
Frangible Yam, but in Castle Keves (you haven't been here yet if you are following this guide sequentially.)"