My step-mom's cat weights 25 pounds. He's not fat though. He's just big boned. And when it's time to clean up the big guy, we call Sonoran Desert Mobile Grooming because if I tried to bathe and groom him, he'd probably claw my face off.
The best thing about the mobile groomers is that they seriously come to your house, so it's a lot less upsetting for your pet. There are no long car rides, just a short walk to the groomer's mobile- that's it.
Although I could hear him yowling all the way inside- even with the TV on- I knew he would be happy once it was all over. And I was right. He looked very spiffy and I could tell he now walked with confidence knowing that his once lackluster fur was now shiny and gleaming.
The prices are reasonable too, and the groomers are very nice, and kind to your pets.