I haven't read the other posts, so sorry if someone already thought of it:
Dynamite:
If hit by a
physical attack, the holder immediately uses Explosion (regardless of whether or not they have already attacked that turn). Possible Secondary Effect: After 5 turns, the holder uses Explosion.
So basically, it's like having Explosion as a 5th attack that is used whenever your opponent feels smart enough to hit you. Think it's a bit violent for Nintendo? They friggin made Guillotine an attack, didn't they?
Useful? Heck yeah!
-Need to stop that pesky sweeper? No problem! Send out Dynamite-holder.
-Put it on a fragile sweeper! It's gonna die from that hit anyway.
-Item Swapping (imagine Trick + Pursuit combo)
-Fling (powerful much?)
-Taunt (screwed much?)
And probably a bunch more...
I was building a team just now and needed a miracle sweeper counter. Viola! Insta-Explosion. Imagine the wtf effect this item would bring to the game.