Mashima plays XI.
Pisces is Leviathan, duh.
....you know.... that would make a lot of sense... Lucy's ability is a lot like FFXI smns! Only the gold keys (avatars) are ever really useful while the silver keys (elementals) exist and are far more common, we never see her use them, save random specialized situations and plue for the sake of him being plue.
Taurus -> Titan (The big guy)
Cancer -> Ifrit (The rarely used claw guy)
Aquarius -> Shiva (The super strong icequeen (Ok, shiva's not super strong, but the only avatars I've seen get regular use for the entire time I've played are her and garuda, others fade in and out)
Virgo -> Garuda (The useful, kinky one)
Sagittarius -> Ramuh (The rarely used awkward one (horse hat, ramuh's gigantic ******* eyebrows, etc)
Leo -> Fenrir (The loyal powerhouse)
Scorpio -> Diabolos (The specialized powerhouse (sleep-based vs sand based)
Gemini -> Carbuncle (The cute one)
Aries -> Alexander (The defensive one)
Capricorn -> Odin (The situationally strong one (Presumably))
Pisces -> Leviathan (the creepy looking fish one)
Libra -> Pheonix (The... Gravity vs Pheonix.... pheonix are birds and can fly, there's something here to make this work. idk, boobs.)
Ophiuchus -> Bahamut (The oh shi- music queing one)
Natsu -> Sam (Designated Shounen Protagonist Sue (Sam being the sue, Natsu's shown SOME ability to not be totally shounen protagonistic)
Gray -> Drg (The Not-quite-as-strong-but-still-really-strong Rival, but really I only say this because of Gray's Icemake: Gungnir)
Erza -> Pld/War depending on the situation (Team Tank or Melee Weapon Specialist)
Wendy -> Whm (Overly strong healer, with Sky Dragon's Roar being Wendy's Holy II)
Happy/Charle -> The Moogle (They're cute and they can fly)
Gajeel -> Drk (The Other-not-quite-as-strong-but-still-really-strong Rival)
Elfman -> Mnk (The Other-other-not-quite-as-strong-but-still-really-strong Rival, but with some tankability)
Lily -> Pup (The unassumingly strong one (Lily's my favorite, this analogue is totally inaccurate, but I don't care because <3 Lily and <3 pup))