This follows Super Smash Bros. for Wii U receiving software update Version 1.0.9 last week that introduced adjustments “for a more pleasant gaming experience.” The maintenance will see online play and rankings unavailable during the three-hour window.
From (approx.) Monday 13th (10pm BST) – Tuesday 14th July (1am BST)
During the maintenance window, the following services may be unavailable.
– Online Play, Rankings etc. for Super Smash Bros. for Wii U
– Online Play, Rankings etc. for Super Smash Bros. for Nintendo 3DS