Don't. In fact, Goofy and Donald will only reduce your hit count. Actually, Ragnarok is your best bet, but since you need to press triangle to perform it, you'll end up asking for Goofy and Donald's assistance and they'll screw it up.
You might want to go a few pages back in the main forum and take a look at a thread titled Pink Agaricus Heartless Frustration. A lengthy discussion on good tactics and get-arounds has taken place there. I hope it benefits you.
EDIT: I know a link would've been great, but I'm posting via mobile now and it's quite hard to link. Sorry.
Oh, so they even reduce the hit count. Good that I didn't use them yet then.
Raganrok? You cannot use special abilities under water as far as I remember. Nonetheless though, since the buttons are mapped to both functions now using special attacks on the Agaricus would be counterproductive anyways.
That seems like a longer issue, lol, I'll make sure to read that once I have some real free time at hand.
/\ Here you go
Pink Agaricus frustration
I'm sorry to say that unless that was included in the HD version, then no. I was never able to get those pesky Heartless to respawn in the PS2 version after fighting them. I agree it is very annoying, and it took me 5 years of owning the game before I managed to get the patience to create the Ultimate Weapon.
So good luck with your trophy hunting,
and hope you enjoy Re:CoM.
Ah, thanks, I'll take a look at this later.
Oh, ok, that means I will probably just cycle through the worlds fighting each rare Heartless at the same time, starting with Traverse going through each world for the rare Heartless, finish with the Neo Shadows in End of the world and then go back to Traverse to start over. Should prevent it from getting boring, nets all of the synthesis items and should respawn them.
I'll let that slide for now anyways, as I'm learning to get into Re: CoM. What irks me the most right now is that I cannot take all cards I have into my deck. Is it wise to always choose the KP-Bonus for Sora at the first ten or so level-ups?
Thanks for posting the link! As for respawning without leaving the world, I've had success only with Jet Balloons. If it doesn't appear, just enter the ship, cross the hallway to one of the holding cells, go up the ladder to Hook's cabin, and exit to the deck again. Repeat until the Jet Balloon appears. I believe the other way around works, too.
For other FM-exclusive Heartless, I don't know if the same trick works, but I don't think it does. You'll have to leave to the map and reenter the world for them to show up again.
Oh, alright, at least one of them works that way.
However, by going in circless through all the worlds should keep this thing from getting too boring.
You can save and soft reset the game if you feel that leaving the world and reentering takes long. This is especially useful for Grand Ghost as reentering Monstro isn't always likely.
I see, but re-entering Monstro is actually pretty easy if you visit a different world before and then warp directly to Monstro, as I've always found him that way.
The Grand Ghost is thankfully one of the easiest of these new Heartless and I have stocked up quite some Elixirs from fighting Wyverns and Defenders so often (and not wasting one Elixir on a secret boss), I could theorethically get 20 or more of the Grand Ghost's drops as giving him an Elixir guarantees you at least one of his drops.