It's a bit random, but I've always thought that seems like an odd decision. Especially given how they've got one for Wario, one for Wario Land and (currently) one for Game & Wario, but they never bothered trademarking the name of the WarioWare series.
Evidence:
http://www.ipo.gov.uk/tmcase/Results/4/EU000758656
Is it due to Intelligent Systems' involvement or something?
Evidence:


http://www.ipo.gov.uk/tmcase/Results/4/EU000758656
Is it due to Intelligent Systems' involvement or something?