Why is Frog Luigi red?

In the previous sheet, Frog Mario was Green, so this is probably just to differentiate between Frog Mario and Frog Luigi, though in hindsight it probably would've been better if Frog Mario was colored Red, and Frog Luigi Green.

On topic, both the alt. Mario and Luigi climbing poses is an interesting idea; especially considering that SMB1's climbing animation is far different compared to SMB3 or World, for instance.

Granted, the idea of alt. poses is nothing new; after all, one that I remembered seeing was from AwesomeZack, but this was (obviously) before SMM2 even came out.