Was There a Mainline Final Fantasy Game on the Wii? No—Only Spin-offs
No mainline numbered Final Fantasy game released on the Wii. Square Enix focused on PS3/Xbox 360 for FFXIII trilogy.
Wii Final Fantasy Titles (Spin-offs)
Final Fantasy Crystal Chronicles: Echoes of Time (2009): Action-RPG, co-op focus. Sequel to GCN original.
Final Fantasy Crystal Chronicles: My Life as a King (2009): WiiWare city-builder/sim.
Final Fantasy Fables: Chocobo's Dungeon (2008): Roguelite dungeon crawler (Chocobo protagonist).
Final Fantasy Tactics A2: Grimoire of the Rift (2007 JP / 2008 NA/EU): **Nintendo DS** game. *Not on Wii.* (Listed here for context as contemporary Nintendo platform tactics entry).
Why No Mainline?
Wii hardware (GameCube architecture) couldn't run FFXIII's Crystal Tools engine.
Square Enix prioritized HD consoles for flagship RPGs.