Pinsirite Cobalion's difficulty keeping its health up can be a bit of a nuisance in longer matches (Though Wish support from Sablenite Blissey can largely handle that), exacerbated by switching its typing to being neutral to Stealth Rock instead of doubly resistant, but yeah it's a surprisingly good Pokemon/Mega Stone combination. Its movepool is surprisingly broad, as well, giving it the ability to custom-beat certain kinds of checks. 108 pre-Mega Speed is also excellent, as so many of the meta's threats actually have less than that as a base Speed -Pinsirite Cobalion will tend to outspeed things both before and after Mega Evolution, which can be killer.
Historically, it's also had the advantage that people almost always turn to either Fighting or Ground for trying to beat it, and it becomes neutral to the first and immune to the second. It can very often get a Swords Dance up on Pokemon expecting to OHKO it easily, and then stomp them. As it becomes better-known, that advantage will tend to go away, as I don't think Cobalion has any other Mega Stones that work that well for it -I suppose Altarianite is workable on it- and so it will become the default expectation that it's Pinsirite, but classically the surprise advantage was big.
Historically, it's also had the advantage that people almost always turn to either Fighting or Ground for trying to beat it, and it becomes neutral to the first and immune to the second. It can very often get a Swords Dance up on Pokemon expecting to OHKO it easily, and then stomp them. As it becomes better-known, that advantage will tend to go away, as I don't think Cobalion has any other Mega Stones that work that well for it -I suppose Altarianite is workable on it- and so it will become the default expectation that it's Pinsirite, but classically the surprise advantage was big.
