Monster Arena Originals Help
Earth Eater:
If your party's armor has Deathproof, you're good. Even with Auto Phoenix, you should be just fine. Cast Hastega first, as always, then nail it with Quick Hit. It will counter with Megaton Punch, which causes Death. After 2 hits dealing 90,000+ damage, it will fall over. Keep using Quick Hit. It will counter with Flare every time, so it helps if you have armor with Auto Shell, and a 255 Magic Defense. Anyway, just pound it with Quick Hit over and over, and it'll be over in a minute or so.
Greater Sphere:
Cast Hastega. Make sure you have armor with Auto Shell, and a high Magic Defense; at least 225. You can hit him with Quick Hit, but he'll counter with Ultima, which is why you need a high Magic Defense. That's basically it.
Catastrophe:
Okay, seriously, this one is so easy, you might not even need Hastega. Just use Quick Hit over and over again and you'll win.
Th'uban
A bit harder. Forget using Hastega, it would be better if your armor had Auto Haste, as well as Auto Protect and Auto Shell. Aslo, Break HP Limit is absolutley needed if you want to survive Convergence. You can either Quick Hit it for an hour, or you could cast Doom and just try to survive until it reaches zero. Every time you attack it, it counters with Condemn, which dispels all magic effects on your Party (i.e. Haste, Protect). It has an attack sequence. First, it claws one of your members. Next, it casts Rainbow, which inflicts status ailments. Then, it will use defensive magic spells, Protect, Shell, and Regen. Finally, it uses Convergence, which does a good 50,000+ damage if you have Shell and 255 magic defense. Just choose a strategy. Quick Hit or Doom Either way, you still have a chance.
Neslug
This one's annoying. Make sure your party has Wakka in it, and all three members have full overdrive and know the ability Entrust. First, cast Hastega. Then, use Wakka's overdrive Attack Reels (and try not to screw up). Then, have one of the other two members use Entrust on Wakka. Then, use Attack Reels again. Repeat this with the other member. That should take care of the shell. Then, just use Quick hit. That ends it.
Ultima Buster
This guy is number two on my Top 5 Most Annoying FFX Monsters. First, make sure everyone has Strength, Defense, and magic Defense at 255. Make sure their armor has Auto Phoenix, Auto Protect, Auto Shell, and Auto Regen (These four abilities together make Assault Weapons (i.e. Assault Shield, Assault Bracer)). First, hit the arms. Then, kill the head with Wakka's ball. Then, quick hit it until the arms regenerate. Then kill the arms again. They will regenerate every few minutes, so just kill them every time. It ends pretty fast after that.
Shinryu
Underwater battle, so you only got Rikku, Wakka, and Tidus. Make sure their overdrives are full. If their armor all has Auto Phoenix, Auto Potion, Auto Shell, and Auto Protect, you should be good. Use Rikkus mix. Mix two Wings to Discovery to get Trio of 9999. This helps tremendously with Auto Potion and Auto Phoenix. Now, just use Blitz Ace and Attack Reels. Piece of cake.
Nemesis:
See, I haven't gotten him yet because I need to capture one more fricking Tonberry. (

) So, I'll post him later.
Edit: Aug 21, 12 12:00pm