No, the definition is the same. But a lot of people use them interchangeably without realising there's a difference, and I was being a bit lax with my usage.
Thank you very much, we almost thought we might offend anyone seriously when inisting too hard on the definition.
However, we find your definition lax in a another way. Defining checks and counter should happen in a closed enviroment and under the assumption of every possible decision the opponent can make (accuracy is a decision, crits are not unless crit stage 3). When you start applying strategy to that you start to falsify the results by assuming that the opponent will always act as predicted - in which case you don't have even ground anymore. For example, the opponent will never spam PuP when they see Ditto in the Team Preview, that's why we will overlook that example.
Secondly, I forgot to mention Thundurus has Life Orb, which guarantees an OHKO on a Mega Kanga with an offensive build.
252 SpA Life Orb Thundurus Focus Blast vs. 0 HP / 4 SpD Mega Kangaskhan: 330-390 (94 - 111.1%) -- 68.8% chance to OHKO
Combined with the shaky accuracy you roughly have a chance of 48.16% to beat offensive Kangaskhan. Thundurus cannot be Modest because it would lose the speed check in that case. A hypothetical battle at full health between those two is basically a coin toss, just that Kanga wins on edge, too.
From that we deduce that you are actually using Thundurus Therian.
252 SpA Life Orb Thundurus-T Focus Blast vs. 0 HP / 4 SpD Mega Kangaskhan: 367-434 (104.5 - 123.6%) -- guaranteed OHKO
It is still no counter because it will lose when it switches in PuP (+ Sucker Punch) or Return but at least it can check (Focus Miss still sucks, though).
To elaborate, Aggron would switch into a predicted Return in order to counter, unless it had already mega-evolved. And those calculations are misleading, since they assume Power-Up Punch has been used, which will not be the case usually. These are the correct calculations:
252+ Atk Parental Bond Mega Kangaskhan Earthquake vs. 252 HP / 0 Def Filter Mega Aggron: 67-81 (37.8 - 45.7%) -- guaranteed 3HKO [even better than I remembered]
Actually, our calculations are accurate. Assuming they have even ground, Mega-Aggron will most likely fail to OHKO Kanga, which allows her to set up PuP.
Then the calculation with Earthquake applies; she is faster and counting the prior damage from PuP it is a straight OHKO.
In that order:
Kanga uses PuP
Aggron uses Superpower (fails 87,5% of the times), Defense drop
+2 Kanga uses Earthquake on -1 Aggron - KO
However, what you can do is Iron Head, then Superpower - in that order only.
So out of curiousity, why is Return seemingly the default normal type move on everything? It only has a max power of 102. Wouldn't there be many other types of normal moves that are way better? (I'm asking because I'm debating on what to do with mine. I was briefly thinking of Facade which would have a max power of 210 vs the 153 Return would have (and if Mega Evolved for Kangaskhan, 315 vs 229) OBVIOUSLY it would depend on if they got a status ailment or not, and that was pretty much just the one example I was thinking of, but why is Return pretty much the only normal move anyone ever seems to suggest for anything? It's not THAT powerful (it's not weak, but there are stronger moves and when you trade the damage goes down to the default level anyway, so any time you trade that pokemon, you have to build up it's friend ship again in order to use that move, whereas any other move is at full power as soon as you get the pokemon)
Never underestimate STAB Return. 102 base power is not low; most moves with more than base 100 usually have nasty side effects like shaky accurracy or recoil. Not Return - at +2 with in the combination with Parental Bond it nukes everything that does not resist it.
Facade is fine when it is activated, but unless is is you are stuck with a rather unimpressive base 70 move (imagine STAB 5th gen Hidden Power). Because Kangaskhan has to hold her stone in order to perform, this move is simply too unreliable. You either have to give up your Return or one of the coverage options which is unacceptable.
Amusingly, you haven't mentioned Double-Edge. It is a base 120 move with recoil, which will definitely ensure that you won't kill more than two targets. +2 Return is already strong enough. It
has slightly more immediate power but is unviable for setup sweeping.
Prankster Whimsicott pretty much makes Mega Kangashcaun worthless, Spore and she's ready to be knocked out by any pokemon with a decent fighting type move, fast or not.
Whimsicott does not have Spore. In fact, there is no Prankster Spore - that would be totally broken in Singles.