Personally, I hate Stealth Rocks. It's such a broken move entry hazards are fine but one that does super-effective damage is a bit much. Doing double-super effective damage is even worse. It pretty much cripples fire, bug, flying and ice types and is a death knell for Charizard, Talonflame, Moltes, Articuno, Ho-oh, Scyther, Volcarona, and any number of bug/flying types that sometimes appear in the lower tiers.
I mean, Spikes is quite clearly stated to be a ground type move, right? So why doesn't it do super-effective damage on pokemon like Blaziken, Electivire and Steelix? Why can Aggron, Magcargo or Bastiodon switch into Spikes and not end up half dead? It doesn't make sense to me, it really doesn't.
If you're gonna screw over one group of pokemon, you might as well do it for all the rest. How about we give Electric Terrain the added bonus of zapping the opponent's pokemon the moment they turn up on the field, ruining Gyarados, Swanna and Mantine forever! Or change Grassy Terrain to bring Swampert, Carracosta and Rhyperior crashing to the ground! Or change Toxic Spikes to put Whimsicott out of the running before it can set up anything! Let's have floating icicles that tear into Dragonite, Gliscor and Garchomp like a bear into a beehive! How about a fire hazard for Abomasnow, Scizor and Leavanny, or a fairy hazard for Hydreigon and Scrafty! A psychic hazard for Toxicroak, a bug hazard for Malamar and Cacturne, a water hazard for Camerupt and Golem, a flying hazard for Breloom and Heracross, a steel hazard for Aurorus and Diancie, a fighting hazard for Bisharp and Weavile and a ghost hazard for Hoopa!
Sound unreasonable? Yes it does, but that didn't stop game freak doing it once, so who's to say what the games will be like come Generation 10!?