1-Up Mushroom - might be interesting for Stock matches/Solo modes. Would be rare.
I'm surprised this doesn't already exist considering how awesome (and logical) the idea is. I support it.
• Fairy - would freely float about the stage after spawning. Coming into contact would heal 50% damage.
This too, seems like a perfect new item to represent the Zelda series.
• Spiny Shell - hits whoever has the most lives/KOs depending on the type of match. Others can be caught in the crossfire as well, just like in Mario Kart.
Eh, not sure. Spiny Shells are annoying in Mario Kart, I don't think putting them in Smash Bros will make people very pleased with Nintendo.
• Deku Leaf - Gives players the ability to float while in midair, and dish out a powerful gust on land. Being a magical item, it would dry out after a certain period of time.
And I support this too.
I'd also like to see enemies spawn from crates from time to time like in Melee, but with the advent of Assist Trophies...that might be kinda redundant.
I remember that and thinking it was pretty neat, so yes, crates should spawn enemies every now and again.
Although I presume it was cut for the amount of effort needed, since the Subspace Emissary has STACKS of different enemies. Still, doesn't mean it shouldn't return and heck, having a ton of possible random enemies that could spawn could be awesome.
As far as Pokémon items goes, I was thinking in TMs (Technical Machines), in which you grab one, wear it as a badge item, like the Screw Attack or Franklin Bagde, and you can use a Pokémon move once, for example, let's say Mario grabs a TM13, he launches an Ice Beam, if he grabs TM24, uses Thunderbolt, and so on.
Another idea I have with TMs are "Elemental TMs", which are type-specific TMs (Electric TM, Ice TM, Fire TM, etc.), and while the characters are wearing them, all their attacks become of that type, for example, Kirby grabs a Fire TM, all of his attacks would be of fire/have a fire effect when hitting something.
Like this idea too.