Moves with secondary effects have always been very annoying in every gens.
RBY: Body Slam paralyzing fast threats (30% of the times) such as Alakazam/Starmie/Zapdos/Jolteon (and Tauros when old mechanics) making them much less scary threats and allowing Tauros/Rocks being much more dangerous, Ice Beam / Blizzard with a 10% chance of killing a mon each turn, T-bolt paralysis (10%), Psychic special drops (33.3%) so psychics can beat other psychics with Psychic...
GSC: Body Slam is everywhere and it is even bigger than in RBY (Body Slam Snorlax can beat Miltank/Umbreon/Skarmory with the help of a BSlam paralysis, something it couldn't do otherwise), Thunder having a 30% chance of paralyzing mons (and Zapdos/Raikou with it being everywhere), Ice moves freezes (10%), Fire moves burns (10%), Rock Slide flinches (30%) giving games (Marowak getting a flinch vs Skarmory when its trying to WW or to rest for example), Psychic Sp Def drops (10%), CC having more CH chance, etc
ADV: Body Slam is less common, but its still very annoying (Lax paralyzing DDtar / Aero / Jirachi completely changes the game, and its a 30% chance), and Rock Slide is more common (Ttar and Aero). Everybody has lost to a Rock Slide flinch at the worst moment (and it is 30% as well). Jirachi has a 20% chance of paralyzing/freezing with T-bolt/Ice Punch, a 60% chance of paralyzing with Body Slam or Thunder (so the secondary effect happens more than 50% of the times), and a 20% chance of lowering the Sp Defense of the opponent, something that can let it beat things like Snorlax. Freezes (10% except in the case of Jirachi Ice Punch) are huge in ADV as well. Meteor Mash Attack rise can allow Metagross to beat Bulky Waters only with Meteor Mash.
DPP: Lava Plume was introduced. Lava plume is weaket than Flamethrower, but it has a 30% chance of burning, something that common counters to fire mons hate (think about bulky waters that are not Starmie, tyranitar and dragons). However, stronger options like Fire Blast are generally better unless you are using a defensive set. Jirachi and Togekiss have a 60% flinch rate with Iron Head / Air Slash and a 60% para chance with Thunder/Body Slam. Freeze / Paras / Burns from moves like T-bolt / Ice Beam / FT are still important. Waterfall 20% flinch chance vs things like Skamory have changed games as well, Stone Edge having an extra CH chance.
BW: The move everybody loves (Scald) was introduced. Scald is a move that allows water mons to burn mons like Ferrothorn and grasses in general who otherwise would completely wall them. It is similar to Lava Plume (weaker than Surf but with a 30% chance burn, can burn sweepers that try to set up, and is annoying for walls). However, the difference of power between Scald and Hydro Pump is huge, and sweepers like Keldeo usually prefer to hit as hard as possible and don't want to lose coverage in 2 water moves, so Scald is rarely used in sweepers. The rest is p much the same than DPP.
ORAS: The only difference is that Surf and FT are now weaker, so the difference of power between Hydro Pump / Fire blast or Surf / Flamethrower and Scald / Lava Plume is smaller, making those moves even more viable not only in defensive mons.
So basically we can divide moves with secondary effects in 2 big groups:
a) Moves than have a chance of freezing / burning / paralyzing the opponent, affecting it in the long term. Scald, Lava Plume, Body Slam and Thunder are the main moves here (30% chance). Then you can argue about whats worse: paralysis (makes fast sweepers nearly useless, and they have a 25% chance of getting FP each turn) or Burn (makes physical sweepers nearly useless, and adds residual damage)
b) Moves with a secondary effect that benefits the user in that turn (for example a flinch or an attack raise). A ton of games are won or lost because for example, Excadrill got a key flinch with Iron Head that allowed it to beat Hippowdon. In same cases, this is much worse than a Scald burn or a Body slam para.
Ok, so moves with secondary effects have been a huge factor in every gen. What makes Scald different? Why should we ban Scald now? From what I have seen in this thread, the reasons are:
a) There are a lot of viable users of Scald (not a big fan of this, because there have always been a lot of body slam users. You can argue about paralysis vs burn and what has a bigger impact, but I dont think this makes Scald different. However it is true than in ORAS, and this is about ORAS, scald is the most common move, so discussing about Scald in ORAS instead of other moves with secondary effects makes sense)
b) Scald is super effective vs the type that is inmune to its secondary effect unlike Lava Plume (ok, fair point, although the most common Lava Plume user also has Earth Power to beat Fire mons)
So please, don't say things like:
Just a small thing, here's one SPL replay where I can remember scald changed the outcome of the game.
It has always happened in Pokemon. Secondary effects change games, it is not a Scald problem
You can argue that Scald adds luck to the game, but... luck is already huge in pokemon, although you can limit the most obv luck based cases, such as OHKO moves ban (30% of getting a free kill is definitely something nobody wants) or moves like Double Team that makes this game much worse for example.
So the question is: is Scald really that big compared with other moves with secondary effects (not only status, also things like Iron Head Jirachi that can flinch mons to death)?
I believe that the ultimate result of tiering is to create a better metagame. I define the characteristics which make a metagame good or bad along these lines: A good metagame is one in which moves, Pokemon, abilities, ETC, tend away from creating circumstances where a heavy element of luck is involved. A good metagame also bans moves, Pokemon, abilities, ETC, which are overpowering.
And I completely agree with Bad Ass here. However there is a problem: there are a lot of moves that have a "heavy element of luck involved", Scald is just probably the most common of them in ORAS. In Pokemon luck is everywhere in fact: there are CHs, moves that have a chance (from 10% to 30% depending on the move, or 60% in the case of Jirachi and Togekiss) of having a secondary effect, moves can miss, pokemons are slept a random number of turns (unless rest), paralyzed mons wont attack a 25% of the times, and confused mons wont attack 50% of the times.
Ok, a lot of luck there. So what to do? The best thing you can do is trying to mitigate luck and weighting the probabilities and going with the route that gives you a bigger chance of winning while avoiding luck (yes triple scald burn crit can happen, but thats unlikely).
Going back to Scald, every player should know that Scald is huge in ORAS, and that they should be prepared for it. Defensive and balanced teams have a lot of weapons to easily beat Scald: Magic guard users, Rest (in ORAS is viable again), Natural Cure (Starmie and Celebi especially good), Water Absorb (although Toxic hurts), Refresh (Altaria, Latias...), Heal Bell/Aromatherapy, Poison Heal users when being Toxiced (Loom and even SpDef Gliscor will beat bulky waters with Scald), Regenerator mons (Amoonguss, Tangrowth) that don't like burns but can deal with them or Fire mons that are not weak to Scald (MCharizard X). Offensive teams have a harder time vs Scald, because they have fewer options, but offensive team also fear a lot Body Slam para (especially from Jirachi) even Lava Plume (Scald is more common, but does that not mean that BSlam and Lava Plume are uncommon, especially with Heatran being everywhere). In fact I would say that Offensive teams fear more a well timed flinch (from something like Gyarados or Excadrill).
To sum it up, Scald is very annoying, and it changes games, but would the game really be better without it? Is Scald that broken when compared with other moves with similar effects? Is Scald that good and that game breaking with so few possible answers that deserves a ban?
If we are talking about older gens (like BW), what about Body Slam and Lava Plume? They were huge in older gens, especially Body Slam (Wish Protect BSlam IHead Jirachi being able to beat offensive teams with 2 luck based moves in both BW and DPP for example).