Palkia is Water/Dragon.
His moves consist of:
Water Pulse
Space Rend
Dragon Claw
And I believe, Ancient Power or some other stat-raising ability.

His weaknesses would be Gr*** for one thing, and also Electric, so you're half-way there.
Make sure you have a speed increase attack such as Agility on your Pikachu, and or have
Quick seeds. and make sure you set its
tactic to 'Go after Enemies' so that it will instantly move up when you do, so you're both
close to Palkia. If you're lucky, Pikachu's static ability will stun Palkia for awhile (
also a good idea is to have chimchar learn dig
) on occasion
for you to get some extra hits. If you have Oran Berries with you - USE THEM. But wisely,
don't use them if Palkia is not stunned or slowed with a status condition such a sleep or
stun, or hunger - by hunger seeds. Orbs are useless in this round, try not to use any
objects such as thorns or rocks, just stick to attacking WHENEVER and AS MANY TIMES as you
can.

To future people:
Remember to ALWAYS stock up on items before you go to bed. Not to mention, SAVE so you may
restart the game and prepare. Take advantage of the halway point and save if you have
enough supplies.
Also you could Get a friend that has the game and tell them to get you tons of reviver
seeds and other
useful stuff.