Alright I'm nominating moving Magic Guard from A-tier to S-tier. I'll going to quote my original arguer if you haven't seen it but I'll add some more at the end.
Overall, immunity to hazards makes it great, but all the other stuff combined with it pushes it into S-tier awesomeness. There is a reason why it is the ability of choice for some Pokemon in Balanced Hackmons, where it has to compete with the other s-tier abilities. Really if Magic Guard was distributed to a Poke, paticularly one weak to rock, it can ignore the curse of SR that has affected tons of Pokemon for only their type. There is a reason why Magic Guard took Zam from RU to OU alone.
The barebones of what I am trying to get at is that Magic Guard benefits both defensive walls and the most offensive Pokes, no need to have a special movepool or stats for it. Alright so I want to answer the question on how magic guard can make an unusable Pokemon usable. Let's say Moltres got Magic Guard. Pretty much "unusable" in OU due to a 4x SR weakness, we now have a Poke with some interesting properties. First, it can actually use its decent bulk with roost since it doesn't have to fear hazards anymore. Not only can it switch in more, but afford to run Life Orb, making it a very scary powerful attack. Heck, it can use some boosted Flame Charge+3 special attacks shenangians without Flame Charge feeling like a wasted slot.Alright I think the biggest mistake on the tier (IMO) is that Magic Guard isn't S tier. Let me explain...
- Immunity to all residual damage
- This is essentially the barebones effect of Magic Guard, but that one little sentence encompasses so much that even I underestimate how significant that is. The big factor about this residual damage business is immunity to all hazards. The ability switch in and out freely makes you a much more "mobile" player and a bane to stall teams. Eliminating the ability for opposing Pokemon to get crucial KO's is huge and having the ability to use a type weak to rock without any repercussions is very nice (case in point). Your entire team benefits from Magic Guard by gaining a status absorber and these abusers seek out status. You can play tricks with Toxic Orb and Flame Orb, but when you receive a Poison or Burn you have a sweeper that can't be paralyzed or slept .(most relevant here).- Huge increase in power
- The free Life Orb is known by most, but it is pretty important. Retaining your bulk and longevity with Life Orb and being immune to its negative effect that was designed to counteract its huge upsides is pretty awesome. While the most popular Magic Guard users are Reuniclus and Alakazam in OU, I don't think they show Magic Guard's offensive potential the most. That title belongs to Clefable. Clefable shows us that stuff as weak as her can be utilized a wallbreaker and another interesting side effect of Magic Guard: the lack of recoil on moves. In a way, Magic Guard acts as a mini-Sheer Force. If any Pokemon was given Magic Guard, they could easily upgrade their movepool to much more fearsome options. The most common upgrades being return to double edge, fire punch to flare blitz, and brave bird everything.- Gureenteed Revenge Kill
- This is one of the niche uses of Magic Guard and one of the reasons why Zam was put into the spotlight. A Magic Guard user can effectively put a stop to a pokemon's sweep with a guareenteed revenge kill. Having the ability to just minimize the damage of a sweep with just the presence of a revenge killer I think is really big. There is also counter-coat shenanigans (I am waiting for you counter-sash zam :*[ )- How is this put into practice? / inviable to viable
- Alright the most popular Magic Guard abusers have been made by their ability, let's take a look. Reuniclus, the most popular of all Magic Guard abusers, has a truly abysmal stat spread. It would have been just another generic psychic type in UU had it not been for Magic Guard. At the peak of its popularity, Reuniclus had a small following for being banworthy, due to maiming offensive teams with its TR set (can you say hydreigon power with LO outspeeding everything?) or putting a full stop to defensive teams with its CM set. We had Zam pull a Gastrodon and go from the depths of RU to OU with just the introduction of Magic Guard in one tiering cycle. Lastly, we have Sigiglyph. With a high profile rmt introducing him, he saw an increase with competing with the bad boys in OU from I believe NU (I think RU wasn't made at the time). Sigiglyph could never pull off his unique, standard set without Magic Guard.
TL;DR Magic Guard acting as a free LO boost (mini-sheer force), status immunity, same effect as rock head, and complete immunity to hazards (which some pokes would kill for) make it too good just to be placed within the A tier abilities. You get a huge increase in both attacking power and longevity with just one ability.
Overall, immunity to hazards makes it great, but all the other stuff combined with it pushes it into S-tier awesomeness. There is a reason why it is the ability of choice for some Pokemon in Balanced Hackmons, where it has to compete with the other s-tier abilities. Really if Magic Guard was distributed to a Poke, paticularly one weak to rock, it can ignore the curse of SR that has affected tons of Pokemon for only their type. There is a reason why Magic Guard took Zam from RU to OU alone.