the 3 slot helicopter (worth 15000 i think) is the plane i finished this game with. it has a vacuum that sort gets the money around it, the fastest (and cheapest investment) easily breezed through the levels and buy the minigun(bought the missile, upgraded it a bit but skipped the rest of the weapons XD).
thunder dragon is my favorite since it can fly, has a high hp, and its 'shock skill' is long ranged and is spammable. to use it just use the yellow egg (killing the thunder dragon) character -> hatch, then kill two creatures for it to transform into a thunder dragon.
the boss is quite easy if you know how to abuse your berserk.
generally what i do is go bullet time when my berserk bar is full and quickly approach the boss, when near, activate berserk, go inside the boss and watch his life go down(you are invincible during berserk), just when your special is about to stop, escape. do this correctly for 4-5 times and the boss will die easily! hope it would help ^_^
the female character of south desert (Diana) sucks at first, but when you acquire the third katar skill (meteor shower), the game gets easier. The skill doesn't miss and the damage is a large area. Once you arranged an army of elite assassins bought from the capital. The game should be a walk in the park. ^_^
nice game, gets easy after you get the pattern!
i got most of my combos during the time the head charges for the beam, just go the opposite direction of the head and press 'A' like crazy! it will get pushed by your attacks so the beam won't hurt you!