It's probably the best to ask that in the Research thread, or have a search around first. Also if Raticate got his Guts to trigger I'd rather use Facade than Me First, which has more universal uses. :]
There's no real if there with Toxic/Burn Orb, Raticate's defenses are too pitiful to take a hit anyway, so losing a percentage in exchnage for doing something before a gruesome death is preferable.
Consider the following:
Raticates Facade (with status): 210 BP
Raticate's MF'd Return: 229 BP
Not much boost here over Facade, but since Jolly Raticate with Guts has 391 attack, it needs whatever boost it can get.
Supereffective moves:
Shadow Claw on Ghosts: 210 BP
Brick Break on Normals: 225 BP
Dragon Claw on Dragons: 240 BP
Earthquake on Rocks/Steels: 300 BP
Close Combat on Normals: 360 BP
Meteoric Swarm on Dragons: 420 BP (but off the crappy 136 SA...)
Earthquake is the keeper here. Switch this in after a CBTar or CBGross kill and tear them a new one. Guts MF'd EQ Does 96-100% to CBGross. DClaw does a similar number on Mence but not Gablias. BB and CC you'll see less of, but they're there.