Beat Giant Ghostkerchief Every Time
To do this your pet can have ANY stats, the only things required for this are :
1x Engraved Chakram
1x Leaf Shield
Total Cost : 70k
For this to work start of by fighting Chia Clown (or anyone) and get you health to under 11.
Once you achieve that withdraw from the fight, and proceed to fight Giant Ghostkerchief.
Now all you have to do is choose your Leaf Shield and Engraved Chakram every turn and fierce attack.
He will only use his Prismatic Mirror, and Ghostkershield. By using the Engraved Chakram you will bypass the Prismatic Mirror,
The Ghostkershield will only partially block your attack so you should get some damage through.
Please note this was tested with 85 and 55 STR boost, I believe this can be done with any STR boost but I am not 100% certain.