I've only ever bathed Felicity when she was a kitten and she had a digestive problem when she first arrived.
Tippy, Felicity and Adelaide weigh between 7 and 9 pounds - I wouldn't attempt to bathe any of them unless it was absolutely necessary. Mainly because I'd only be able to do it once as I wouldn't have any arms left afterwards
Lily - that's a different story, if she wants to sleep in my bed with me she gets a bath and that's that!!! But, she's only 3.5 pounds and not likely to get much heavier, so I can easily overpower her