Well the Kimbo punches were obviously faked.

The punches certainly looked real enough so my guess is that Blain was wearing some kind of stomach (flesh coloured) shielding.

That would explain why he only lifted his top a little rather than took it off like a real man would do.

It also explains why he looked a bit fat.

He was probably wearing one of those 300 abs packs.

The bullet catch not sure how he did it but he even said specifically beforehand that it wasn't real so obviously he didn't really get shot in the mouth, else he would be dead.