Washer Banjo

Banjo-Kazooie
In Banjo-Kazooie, the transformation is simply supposed to be a joke. Mumbo might turn you into one by accident, but after a note of caution for you to stand still, he will turn you into the proper transformation.

By completing all of Bottles' Bonus Challenges, you can unlock a cheat that will turn you into the washing machine. It has access to all of Banjo's moves, excluding Wading Boots and Running Shoes. While Mumbo is against the idea and claims he won't transform you while being a washing machine, he will still transform you (for free if you haven't paid yet!), but he'll turn you back into the washing machine.

Banjo-Tooie
In Banjo-Tooie, the Washer is the native transformation of Grunty Industries. Unlike the one in Banjo-Kazooie, this one has wheels, the largest energy bar in the game (up to eleven honeycombs) and doesn't look unhappy. The Washer can attack by firing old smelly underpants by pressing Z (aim with C Up), and it can help the Skivvy rabbits by washing their overalls. Its immense weight allows it to press a certain switch in the level, but also impairs its jumping ability.