I'm just gonna ask you right now if you've actually used him.
Lol what he's said is exactly correct, and this is coming from the guy (me) who has indeed extensively used mega gallade (its the first one i used lol).
Its ability to fire off a single attack is overstated, its bulk is overestimated, its speedtier isn't as relevant as it used to be, its ability is horseshit, and its defensive typing blows.
We haven't even mentioned how you need to find a place and time to safely mega evolve because you're jumping all the way down from 80.
Ultimately, if we go by your train of thought
Albacore , we assume that because mega gallade is bulky, it is good against offensive teams too.
Fact is, its not as bulky as you'd like it to be. It lacks reliable recovery, it lacks great resists, it lacks a great defensive ability (before or after mevo), and to top it off it lacks good priority. Ultimately, you can take ONE hit against offense, and you usually want to use that one hit to set up. Unfortunately, since without priority and in a less than ideal speed tier, even after you set up you'll never really sweep a competent offense team being handled by a player with actual brains. Sure, it looks pretty bulky on paper, and that's what hyped me up too! But ultimately in practice its reduced to a hit-and-run playstyle, only taking a hit when the game depends on it.
So now that we've covered its bulk, lets move onto its actual speed, and prowess against offense. Basically, its not as good as you make it sound. It takes one hit perhaps, and can use that turn to blow holes with CC or set up against offense which is usually fruitless on its own. Unfortunately, there are many many more relevant mons that have entered the 110 speed tier, such as mega diancie and mega metagross, all of which have the capacity to revenge kill you, forcing you to rely on a speed tie to get past them (lets be real sneak ain't doing shit to metagross lmao). Sure, lati@s often run hp fire which means you win against them, but then you have to take into account their scarfed forms are catching on too. Other scarved mons like keldeo are also starting to get some attention, and ultimately offense has gotten faster. now u have mega gallade, a mon that can take a hit and hit back at best, lacks priority, has many weaknesses, and resists zero relevant priority moves bar mach. its matchup against offense is REALLY overstated.
Finally, its matchup against stall kinda blows then the best kind of stall these days always carries your hard counter. Lol have fun. Even megas that fit on bulky offense teams, like mega slowbro and mega altaria, do a pretty good job and giving mega gallade a hard time.
I probably said it before but lack of bulk+priority+useful ability leaves it less useful against offense than one would desire and the omnipotence of your hard counter on stall teams leaves it pretty subpar there too.
Its an A+ mon, not S.
No, I've only ever played against it. But that's why I decided to agree with the other guy who doubted him as A+ rank, because I pretty much feel relieved when I see it in team preview (because I haven't deviated much from mega slowbro at all)
that's probably me :3