I recently saw a video on YouTube about the tiltmeter app used in beyblade is it legal?
Well, it looks like a launcher mod and those have been outlawed from what I've heard so I'd assume that it is illegal.
Edit: I looked at the comments, yeah. Its attached on by scotch tape. Meaning its a mod.
This doesn't belong here. Please ask Beyblade-related questions like that in the "Ask a question, get an answer!" topic next time.