Well, since !Evertte87
submit his own Tiff training to become stronger. But I think my idea is Knuckle Joe train her before Tiff, Tuff, Meta Knight and Kirby arrives to Mushroom Kingdom.
This is the part of flashback of SMBGT about Asylus' Rampage in Dreamland
P.S. Sorry for background, it's from Batman Forever (SNES)
Sprites by ~FaisalAden
Super Mario Bros GT - The Grand Adventure (c) Me ~xXKaijuKing91Xx
Characters (c) Nintendo and HAL Laboratory