How to Unlock Wracky Guide
In order to unlock Wracky you'll need to reach the 7th rank as a trainer, which requires you to beat two battles after the S rank cup. Once you do this, assuming your Monster has high fame a fan will send you a Doll that Colt finds extremely creepy. He'll ask you if he can throw the Doll away, your answer doesn't matter but if you do choose to throw it away, it'll show up the next week and freak Colt out more.
After a fan sends you this Doll all you need to do is have one Monster on your ranch kick the bucket. It can get injured in a battle and die that way or you can work a Monster to an early grave through stressful training regimens, the choice is yours. The day after your Monster dies, its spirit will possess the Wracky Doll and it'll come alive.
Wracky is arguably one of the hardest Monsters in the entire game for a player to raise. He bugs the player for gifts constantly and when you first start raising him Cheats and Fails on drills a lot of the time. He also comes with insanely low status and very low stat gains in those stats. If you want to build a good Wracky you'll need to spend a large portion of his life building up his Skill despite him having extremely low gains in it.
The second part of Wracky's life you'll want to raise his Intelligence, Speed and Defense/Life as an after thought. Basically, Wracky is a RNG one hit wonder machine. His goal is to one shot enemies as fast as possible while dodging everything thrown at him. I raised my Wracky this way and he basically dominated every Monster Tournament, it was quite impressive actually.