neslug is easy, if you have attack reels... it also helps if your doin 99 999 damage.

heres the low down on Neslug: HP - 4 000 000. When his HP drops below 2 000 000, he will go into his shell and heal himself to full health (GREAT!!).

what you need to do is get his health as close to 2 000 000 without doing more than 2 000 000 damage. this is easiest if you do 20 attacks of 99 999 (1 999 980 damage). after this, have wakka use attack reels (12 x 99 999) which will break Neslug's shell!!! yay!!!

after this, finish him off quickly because he will keep attacking your party with slime, which is pretty annoying (esp if you dont have ribbon).

hope that helps!!