Okay, I've worked out how this fits in the anime.
First, Kenta can't get his beyblade to evolve, so, he ends up crying to zeo for whatever reason and zeo is like "fine guy shut up already jeez, have flame byxis I don't even care any more damn".
Kenta still isn't happy, and goes whining to Madoka. Madoka gets sick of the whining and is like "look gimme Sagittario and Byxis and I'll see if I can make it evolve maybe there's something holding it back"
Madoka jams together the two flames with a little modification, gives 230WD a little bit of paint, and comes out and pretends it "evolved before her eyes".
Kenta is now happy, and the shock of him suddenly not whining kills diablo. The End.