Yes you can. Obviously Fusion Recovery must target a Polymerization, not Dark Fusion.
Chat with our AI personalities
You use Buster Blader, Dark Magician and Polymerization.
No, Elemental Hero Dark Gaia cannot be special summoned, except by the effect of 'Dark Fusion'. You cannot use any other special summon methods (like Monster Reborn), or even other fusion summon methods (Polymerization, Re-Fusion, Future Fusion).
Dark Paladin and Dark Flare Knight both list Dark Magician as a Fusion Material monster.
Yes, "Future Fusion" can be used for "Rainbow Neos" by sending an "Elemental Hero Neos" and a "Rainbow Dragon" or "Dark Rainbow Dragon" from your deck to the Graveyard.
Fusion Recovery