Ok if you want to use that logic, then sure switch out and give them a free SD boost etc and let them then ravage your team. Regardless, its pointless attempting to theorymon the match by saying "I can then switch out to a perfect counter to them that doesn't care if they just got +2"
The point being, that the other "filler" moves do have uses, and both alexwolf and I see them as being more useful than endeavor in the majority of battles. However, I do see the merit in Endeavor, which is why I mentioned it in AC. If you do still believe that Endeavor should get a main slash (something I don't think I would be wholly opposed to) then it may be more helpful to provide concrete evidence (lead matchups etc) rather than random theorymonning which has little to no use.