And the mome rath
Skyblade outgrabe
Not true. The Power Hydra's final form, the Gigant Hydra, is more powerful than the Ultima Weapon. It also has a supremely awesome magazine of 1 round (so you don't have to worry about running out of ammo).
I didn't realise that... what's the succession of upgrades needed to get it? Also, how is a 1 round magazine any use?
Ultima Weapon lets you spam unholy amounts of death up to 33 times before reloading, since it's a Cerberus-type triple revolver with 99 round magazine capacity. In the 'defend WRO headquarters from the attacking helicopters' mission, you can one or two-shot all the choppers while running around on foot. It's that awesome.
Does the item carryover from a completed game only work if the new game is an Extra Hard game?
Yup.