Hey there
firstly, '2.) Skarmory can cripple Mega Metagross enough with Counter that another Pokemon can come and finish it off easily.'
no, that's problematic English usage and i'd argue that's not crippling; as a fairly fast mon that sometimes carries prio, M-gross can arguably survive despite being at low health. It's pretty limiting and it can no longer switch into a lot of stuff, but crippling? You're not stopping it from still outspeeding stuff and just hitting hard as well, which is what most crippling things do.
What I really came to ask you is to get rid of the shitty definitions of Check and Counter. Let's be honest; if you go and actually read MattL's article, you pretty much notice that he doesn't know what he's talking about; Mamoswine checks Bisharp by dint of revenge killing it, but can't switch into any move but Sucker Punch and then take a Sucker Punch afterwards (I.e. Knock Off + Sucker KOes, Swords Dance -> +2 Sucker Punch Koes, Iron Head probably just Koes but Sucker Punch is still there and all). This is the main problem with the check definition, i.e. that it focuses too much on bottom-feeder checks instead of emphasizing that, while those are technically checks, you really want more robust checks that can actually switch into moves, and TBH many advanced players wouldn't refer to revenge killers as checks for the most part.
Oh yeah, all of his named counters can only safely switch in once, which is pretty hilarious and all but emphasizes the main flaw in the counters explanation (well, kinda)
Explanation: Pokémon A counters Pokémon B if Pokémon A can manually switch into Pokémon B and still win every time, even under the worst case scenario, without factoring in hax.
So i see in your example you took 'every time' to mean that healing is involved, which is the big catch with how he took it in his article and arguably how you can take it in general. If you don't have the ability to heal off damage, oftentimes you can just be worn down pretty easily and fail to be a counter. Be nice if the explanation was made mildly stronger on this point, though your example is a pretty good explanation of an actual counter.