Chumley Huffington is one of the most underated duelists of GX. His boss monster is stronger than "Obelisk the Tormentor" and so close to the ATK of "Blue-Eyes Ultimate Dragon", the strongest fusion non-effect monster.
Basically there are 3 ways to summon "Master of Oz":
1) Running a bricky deck with Big Koala/Des Kangaroo and "Recycling Fusion Plant" to summon multiple copies of "Master of Oz".
2) Use "Cattle Call" to summon "Master of Oz" but it can't attack and is kind of useless.
3) The most efficient way of summoning "Master of Oz" is to use the Earth Hex with "Des Kangaroo" on field without the need of a fusion spell card.
----------Why to summon Master of Oz ?----------
1) You can burn your opponent's LP with "Vengeful Servant" and "Shien's Spy".
2) Use "Cattle Call" and then with "Number 64: Ronin Raccoon Sandayu" you can copy it's attack.
3) With "Wild Nature's Release" and the help of "Sea Koala" to OTK your opponent if he has only 1 monster on his field.
4) It's one of the strongest monsters in the game with the cost of 2 cards (Des Kangaroo + Earth Hex).
One pretty nice addition to this deck could be "Forbidden Lance" or "Forbidden Dress" which can protect "Master of Oz" from destruction by "Wild Nature's Release" or opponent's cards, but for some reason it can't protect it from "Cattle Call" effects and that's why it's not inside my approach of this deck.
I've tried "Threatening Roar" too, but "Waboku" works better with flip-effect monsters.
One pretty big problem I've faced, is that I cannot special summon "Master of Oz" from grave with "Monster Reborn" even if it was fusion summoned with materials and not by "Cattle Call". So you can't rely on such a mechanic to cheat summon it.
While some cards have similar names (koala / Des), this is not a real archetype at all. But you can always use "Des Wombat" with "Ring of destruction" if you really want it. The Zoodiac engine is quite big and I don't recommend you to use it at all. Most of your monsters in this deck are level 2 or 4 and there are better options that are most efficient to use.