HP Grass: Grass Knot slightly beats it in the long run. Teched HP Grass does beat it when it has 20, 40, and 80 BP but once GK hits 100 in power, HP lost it's usefulness
HP Fire: If it doesn't learn Flamethrower, Fire Blast, Heat Wave, or Lava Plume than yes Tech HP Fire has some use. If it learns Flamethrower/Fire Blast/Heat Wave then you wouldn't need HP Fire in the first place. If it only learns Lava Plume then it would be a question of Power vs Effect.
HP Ice: Same with HP Fire except replace FT and others with Ice Beam and Blizzard.
HP Electric: Same has HP Fire discussion.
HP Ground: Why not just use Earth Power? Same strenght has a Tech HP 60 Ground.
HP Bug: Tech Silver Wind is already here for you, BTW it OHKOs 252/0 Celebi
HP Flying: I just this could used on Heracross but that's about it.
HP Fighting: Focus Blast has shaky accuracy, I don't believe people will buy the use of magnetism to explain how it has Aura Sphere within it's movepool. Hits T-Tar for extreme damage ([B]80.2% - 95.05%[/B] in Sand to be exact) but can't think of anyone else that's screwed from eating Tech Fighting.
HP Dark: Useful against Ghost and Psychic types?
HP Ghost: Same thing =/
HP Water: Tech Water Pulse is just as powerful with the added confusion effect, but what in God's name are you going to use it on?
HP Steel: Erh....got nothing
HP Rock: Power Gem that shitty to not use it?
HP Poison: What are you, crazy?
HP Dragon: Kingdra...that's about it.