This is a grey area. The mod itself is legal—it consists of fan-made tracks and scripts. However, the (the base Mario Kart Wii engine). Distributing the pre-patched WBFS is technically copyright infringement.
Among the various versions and formats, occupies a special niche. This specific release is tailored for USB loaders on the original Nintendo Wii and Wii U (vWii). This article explores what v1.03 is, why the WBFS format matters, how to install it, and the legal considerations surrounding it. ctgp revolution v1.03 wbfs
CTGP Revolution is a massive fan-made expansion. It adds over to Mario Kart Wii. This is a grey area