During my Gym and E4 run I don't really worry about HM Slaves, and just teach my party members the HMs.
I don't know...
I wish they hadn't added Rock Climb.....and i think you shouldn't need any HMs to get to Red....as that sucks, because you can't have your full team.
I'm gonna use my Tropius from Platinum (Cut,Rock Smash,Fly,Strength), and my Gyarados can have Surf,Waterfall,Whirlpool,Rock Climb.