Maybe it's not about the weapons? The fact that he was extensively tested by the battle admins makes me think that there's something more.
Tried the just to see if it would do anything.
It didn't.
I've looked up the pets stats that have beaten him and its Cranberry's Visla (3 losses, 1 win) and Purge's Goddess (2 losses, 1 win) I'm trying to look at their stats, books read, foods eaten and see if I sense a trend with those numbers.
- That is pretty nice.
I accept 451 sP! Magical Arctic Star Potion been put in your items.
ZOMG, was that a booster I just grabbed from the AA? Wow, that's a first since the revamp.
The extensive testing may have had more to do with them making sure that certain weapons have the proper effect against him, like they don't do anything. There could be something that will work, we just haven't figured it out yet.
Is something an "accidental weapon" if it shows up in my armory as Tier 0?
Yes. It just sits in my battle set. I can't use it.
What is it?
8887/9512 I got to here and then gave up. I tried a plain brown feather (to tickle him). It broke and was gone forever. Tried the Awesomely Totally Bent Pokey Stick to poke him to death, didn't work.

I tried searching for any goat related weapons (Three Billy Goats Gruff), but to no avail. But now I'm wondering if a Sheeta can do it...
Dark Death Potion Dark Earth Potion Dark Life Potion Dark Light Potion Dark Magma Potion Forj Magma Shard Skull Fungus Turkey Elixir
all of these are tier 0 weapons

- I feel like if they were testing weapons, neither of them would have taken any losses, but they both have losses against him. If it some sort of weapon gimmick, I don't think they there would have been multiple losses. I mean the challenger only has 10 in all it's stats, even if it had some sort of coding that changed it's weapons when you use certain weapons, unless it has some ultimate spork of doom weapon (like the slaughtersaurus mass extinction) a loss for a T13 pet would be pretty unlikely. I think there is more likely something with his weapons, that is the key to beating him. My best guess right now is that he just has a shit ton of weapons that block everything, and some that also do damage, and 1 weapon that blocks like 500 of everything instead of all, and it just takes 2million turns for him to use it. It's just a waiting game. But who knows.
My battle pet is a Sheeta, She is getting nowhere...:(