Simple Green and a razor blade.
Let the Simple Green soak in scrape it with the razor then finish it off with soap, water and a Scotch pad or 00 steel wool.
After each cook I clean my grate with a scraper, clean the bottom with a plastic scraper and a cheap chip-brush, and clean the outside with Windex. (Mild glass cleaner was what Weber recommended to clean the exterior with before the new people took over).
If things get gummed up I put it in oven cleaner mode using a hot fire and the gunk tends to burn off by itself. I don’t remember using anything stronger than Dawn.
I’ve also bought a big washtub to soak the smoker grates in hot water & dishwashing detergent which worked great but the weld areas of the grate started to rust.
The new Dawn power wash also works great for cleaning up the rotisserie after a cook. I bet it would do a good job on the grates and bowl.
My tools to clean bowl after each cook. It cleaned this mess up. The chip brushes are 36 for $11 at harbor freight. I buy them for chips on my metal lathe but they are a great cheap brushes for other stuff. The scraper is part of a set at harbor freight.
Outside nothing. Inside I scrape the grill after every cook with a scraper and brush. Occasionally I'll flip the grill over and do the same. The sides I typically will let the heat from the coals take care of that. Once a year or so I'll take a wire wheel on a drill to the grill,