A few bits of advice for Battledome beginners who are trying to beat Mummy Moach. Remember my mantra: everything I ever needed to know about the Battledome, I learned from
http://idb.finalhit.org/ .
1. Mum is very offence-minded. This means that it's possible to take her down in a few hits if you survive them yourself. It also means that you shouldn't use your own Berserk / Fierce Attack too much or you're going to end up getting pummelled. Remember - if one of you uses aggressive tactics, both of you take more damage in that round. If BOTH of you use aggressive tactics, you both take LOTS more damage. Instead, use good faerie abilities, good species abilities or Defend (but remember that if you Defend, both you and your opponent will take less damage in that round).
2. Strength and Defence are measured in levels. Lots of people are stopping at a Str or Def of 50. Don't! Train it up to 55 and you'll get the next boost. The boosts happen at 8, 13, 20, 35, 55, 85, 125... etc. The higher your strength boost, the more damage you'll do with the same weapon. A pet with a strength of 50 will do the same damage as a pet with a strength of 35. Your Defence stat is used in the same way but only when you use a defensive or dual-duty weapon - NOT when you use the Defend stance.
3. Mum does MASSES of earth damage. She also does physical and, to a much lesser extent, air, light and fire. She uses no dark or water. Know what your weapons and shields do! You need some way of defending against earth. Leaf Shield and the less powerful Ugga Marbleshield are solid earth defenders and will also take a bit of physical damage. A Downsize! will halve the damage you take in one turn per battle. A Golden Geraptiku Talisman will help a little, but won't protect you much when that Stone Snowball comes slamming your way and is no good at all against the Moach Pincer. Potions of Concealment will block all earth damage as well as throwing some damage back at Mum, but you can only use them once.
The faerie ability Burrow is great in this battle as it will block almost all earth damage for one turn as well as some of the other icons Mum uses, allowing you to throw your two toughest weapons at Mum without worrying about getting hurt. Sink is much less useful.
For healing, you might try zapping Mum with Drain Life on your first go. (The more HP she has left, the more you'll heal.) Restore, Healing Vapour and Regeneration are all recommended, and all get more effective the more hurt you are.
4. Mum does not have a strong defence. She can block a little earth and physical damage, and can lower all the damage done to both you and her by using Defend. Her Ice Mirror can reflect some of your own light damage back to you. Therefore, any weapon with a combination of water, dark, air and/or fire icons (the more the better) should serve you well. Try to avoid using light and earth weapons if you can. For ideas, see
http://tinyurl.com/32zyr9. Scarab rings will get a few icons through her and every beginning to intermediate battler should really own one or two. If you have around 100k to spend, get a 9-10 iconer like an Ice Club or Cloudy Wand of Storms. (The cloudy wand will be particularly good in this battle as it also blocks a little earth.)
5. Final bit of advice: the best defence is a good offence. If your health is really low and you don't normally battle, this opponent might simply be too tough for you - but try to take her down as fast as possible and she might just be caught by surprise. An enemy this aggressive will flay you without mercy if you're too defensive. The more turns you spend trying to heal or freeze without hurting her, the more turns she'll have to pummel you. If nothing else works, close your eyes, cross your fingers and hit her for all you've got!
EDIT: If you need more advice after reading all through this, I'd be happy to help if I can.
I have lifted a little of your advice for my plot guide. I would really like to link/credit you for this. PM me with your NP username or if you are unhappy with this.