Banning Mega-Metagross will not help fairy, rock, or ice because the next mega in line, imo, will be scizor. Scizor rips apart teams weak to bullet punch moreso than metagross.
I'm not a "god" when it comes to steel or dragon, but I would consider myself rather good since I have made it to #1 with steel and I know one of the best dragon users around to talk about this. Steel vs fighting and dragon is competitive, meaning it definitely isn't one sided.
Fighting, to my understanding and the chart's, generally wins against steel even with mega gross. There usually is a difficulty in mega evolving without damage, and with lower health mach punches and the scarf poke usually kill it.
As for dragon, it really is the same story. Keep in mind dragon is resisted by steel, but even then most dragon types carry a fire or ground move to punish the mega evolve, and then a scarf will put it in a coffin (even scarf shadow ball latios 2hkos).
Meanwhile against psychic...
It isn't a mystery as to why fighting loses to psychic most of the time, but the reason dragon loses, from my layman's perspective, is that the popular mons beat them anyways.
Wisp mew, slowbro (defensive wall), and mega/scarf gardevoir maim dragon. Metagross is just a nice choice that, in all honesty, people aren't picking for dragon but to fight other types.
tl;dr Seems competitive to me, although I think greninja is competitive as well, keep em.
ArVaDa-, what I want to recognize is how you say that "Fighting generally wins against steel even with mega gross." Here's the issue with that -
it's only by a margin of 7.2%. In my opinion, if a type like steel is winning against another WITH a disadvantage nearly just as often as the opposing type, something is wrong. Yes, the objective is to aim for the closest neutrality in terms of type matchups, but when it's solely because of one Pokemon, that's not balance, that's using something powerful to beat what you lose to. In my eyes, it's similar to the Kyurem-W and Skymin situation. Yes, it helped the types against bad matchups, but that doesn't make it any more healthy for the meta (also realize that steel is not in any way bad, as I'm sure we all recognize). Also, any decent player wont try to switch in MegaGross inopportunely, but simply wall the opposition and wait for a switch. What needs to be recognized is that due to the amount of choice items and general un-switchability of Fighting, bringing in MegaGross is a lot easier than you make it out to be. It comes down to the point where so much switching is being done just to get around walls like Skarmory and Ferrothorn (which causes a lot more trouble for Fighting than you would think btw due to the crucial importance of longevity that Ferrothorn stops with things like Leech Seed and Rocky Helmet) that there are always moments where it's easy to just drop in MegaGross on a choice-locked mon or Breloom with a broken sash, that it's sort of ridiculous. All in all, if it takes an extremely offensive type like Fighting constant switching around to beat a type it has
an advantage against, due to one Pokemon, then that Pokemon undoubtedly needs to be at least considered for a ban.
In terms of Dragon, while yes they do have a lot of Fire moves, Ground moves, and Scarfs, not all of them do. Not every Dragon is Scarfed with Fire Blast, unlike a lot of people tend to believe. Again, I want to point out that it takes a considerable amount of switching to get around MegaGross, which offensive types like Fighting and Dragon can't truly handle. Also, once said Fire Blast/Scarf mon is removed, all bets are off. For example, allow me to provide some calcs:
Matchup #1 - 252 SpA Hydreigon Dark Pulse vs. 0 HP / 4 SpD Mega Metagross: 236-278 (78.4 - 92.3%) -- guaranteed 2HKO (Scarf)
252 Atk Tough Claws Mega Metagross Meteor Mash vs. 0 HP / 0 Def Hydreigon: 232-274 (71.3 - 84.3%) -- guaranteed 2HKO (This plus a Bullet Punch and good-bye "MegaGross check")
Matchup #2 - +1 192+ Atk Mega Altaria Earthquake vs. 0 HP / 0 Def Mega Metagross: 214-254 (71 - 84.3%) -- guaranteed 2HKO (AFTER DRAGON DANCE WITH ADAMANT)
252 Atk Tough Claws Mega Metagross Meteor Mash vs. 64 HP / 0 Def Mega Altaria: 392-464 (127.6 - 151.1%) -- guaranteed OHKO
Matchup #3 - 252 Atk Garchomp Earthquake vs. 0 HP / 0 Def Mega Metagross: 230-272 (76.4 - 90.3%) -- guaranteed 2HKO (Scarf)
4 SpA Garchomp Fire Blast vs. 0 HP / 4 SpD Mega Metagross: 122-144 (40.5 - 47.8%) -- guaranteed 3HKO (Second situation, also Scarf when locked into Fire Blast)
252 Atk Tough Claws Mega Metagross Ice Punch vs. 0 HP / 0 Def Garchomp: 496-584 (138.9 - 163.5%) -- guaranteed OHKO (If no Ice Punch, there's always Meteor Mash+Bullet Punch super-combo)
Matchup #4 - 252+ SpA Teravolt Kyurem-B Earth Power vs. 0 HP / 4 SpD Mega Metagross: 188-222 (62.4 - 73.7%) -- guaranteed 2HKO (Scarf - keep in mind Modest LO doesn't kill either)
252 Atk Tough Claws Mega Metagross Meteor Mash vs. 0 HP / 0 Def Kyurem-B: 426-504 (108.9 - 128.9%) -- guaranteed OHKO
Matchup #5 - +1 252 Atk Dragonite Earthquake vs. 0 HP / 0 Def Mega Metagross: 236-278 (78.4 - 92.3%) -- guaranteed 2HKO (This is after a Dragon Dance, and also accounts for Band).
252 Atk Tough Claws Mega Metagross Ice Punch vs. 0 HP / 4 Def Multiscale Dragonite: 246-290 (76.1 - 89.7%) -- guaranteed 2HKO (before Multiscale)
I think we've seen enough. The general trend is clear - sure you can use your Scarf Fire Blast or Earthquake, but it rarely, if ever at all, will kill Metagross. And unless if you have several Scarfs, along with access to Earth Power, Fire Blast, etc, then facing a Metagross will not be fun for you while using dragon. On top of this, when discussing whether or not a Pokemon is OP we can't stray towards this "1v6" state of mind. MegaGross is never alone in these sorts of matchups. Garchomp is locked into EQ or about to use it? Simply switch into Skarmory. Locked into Fire Blast? Heatran. Although it may take some degree of skill, knowing when your opponent is scarfed and about to attempt to kill your MegaGross, and whether they're using Fire Blast, EQ, or Dark Pulse isn't all that hard. Also, I doubt the opponent will have ALL of the mons mentioned above ^. Believe it or not, good Dragon teams usually only have 1 or 2, maybe 3 at most scarves (although I will admit I've seen 5 scarf dragon do work). They won't get up a DDance easily either. And Fire Blast Garchomp, Altaria, and Fire Punch D-Nite aren't all that common, and they definitely won't have them all on the same team (fire moves rarely do too much anyways, Fire Blast from Garchomp barely 2HKOs a Skarmory). Simply put, a decent player will know not to keep in a MegaGross against a Scarf Garchomp and take the safe play accordingly. And when they only have one Fire Blast/EQ mon left, all it takes is for Megagross in, tank said EQ and/or Fire Blast, and sweep.
tl;dr: Although Fighting and Dragon teams do have ways to stop MegaGross, they are often inefficient and unreliable, as most super-effective attacks result in a 2HKO and are responded by Meteor Mash+Bullet Punch - on top of the fact that once the mon or two that the Fighting or Dragon user has to "stop" MegaGross there's not much else they can do to win.