I admit I'm purposefully using the term check/counter a bit looser than the actual definition of the word, but if you're going to argue that something isn't a check/counter by definition
I expect you to know what the definition is and apply it correctly.
To recap the actual definition:
Pokémon A
checks Pokémon B if, when Pokémon A is given a
free switch into Pokémon B, Pokémon A can win every time, even under the worst case scenario, without factoring in hax. (Note: this is under standard field conditions, which is SR, no spikes, no webs, no reflect/ligthscreen)
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.
https://www.smogon.com/smog/issue32/checks-and-counters
Of note:
If a Pokémon gets a "free switch" in, that means it gets to enter the field without the opponent being able to immediately make a move on it. For example, a common way that you get a free switch is after one of your Pokémon faints; your next Pokémon is allowed to enter the field without immediately being attacked. If one of your Pokémon is "manually switched" in, then your Pokémon allows the opponent to make a move without your Pokémon being able to respond in that turn.
Your opponent's move doesn't have to be damaging. If your opponent uses Swords Dance as you manually switch in, your opponent still has an advantage as opposed to if you had gotten a free switch. A manual switch is exactly what it sounds like; the most common way is literally switching out during your turn instead of attacking. There is one subtlety. For example, a Ground-type switching into an Electric-type move will not be affected at all, so this counts as a free switch because the Ground-type incurred no punishment upon switching in.
I've generally shied away from using these definitions lately because I've found that people don't like what the definitions tell them and say "you're wrong" to statements that are
true by definition. For example:
1. Standard Hazard Garchomp is a
counter to Specs Chi-Yu.
Viz:
252 SpA Choice Specs Beads of Ruin Chi-Yu Dark Pulse vs. 252 HP / 4 SpD Garchomp: 306-361 (72.8 - 85.9%) -- guaranteed 2HKO after Stealth Rock (modest is 1/16 to kill with rocks chip)
0 Atk Garchomp Earthquake vs. 0 HP / 4 Def Chi-Yu: 324-384 (129 - 152.9%) -- guaranteed OHKO
Garchomp can switch into any attack and force Chi-Yu out; it is a
counter by definition.
2. Urshifu-Rapid-Strike is a
counter to SD Baxcalibur.
Viz:
252+ Atk Baxcalibur Glaive Rush vs. 0 HP / 4 Def Urshifu-Rapid-Strike: 232-274 (68 - 80.3%) -- guaranteed 2HKO after Stealth Rock
252+ Atk Baxcalibur Ice Shard vs. 0 HP / 4 Def Urshifu-Rapid-Strike: 39-46 (11.4 - 13.4%) -- possible 7HKO after Stealth Rock
252 Atk Urshifu-Rapid-Strike Close Combat vs. 0 HP / 0 Def Baxcalibur: 422-498 (113.7 - 134.2%) -- guaranteed OHKO
Urshifu can switch into any attack and force Baxcalibur out as the combination of Glaive Rush + Ice Shard does not kill; it is a
counter by definition.
3. Zapdos-Galar is a
counter to Black Glasses Adamant Urshifu-Single-Strike:
252+ Atk Black Glasses Urshifu Wicked Blow vs. 0 HP / 0 Def Zapdos-Galar on a critical hit: 132-156 (41.1 - 48.5%) -- guaranteed 3HKO
252+ Atk Black Glasses Urshifu Sucker Punch vs. 0 HP / 0 Def Zapdos-Galar: 82-97 (25.5 - 30.2%) -- guaranteed 4HKO
252 Atk Zapdos-Galar Close Combat vs. 0 HP / 4 Def Urshifu: 380-450 (111.4 - 131.9%) -- guaranteed OHKO
It can come into any move and win 1v1; it is a
counter by definition.
Anyways, now that we have the definitions out the way let's look at some of the bug checks mentioned above:
1. Iron Defense Araquanid is a
counter to Gourging Fire:
+1 252 Atk Gouging Fire Flare Blitz vs. 248 HP / 252+ Def Water Bubble Araquanid: 102-121 (30 - 35.6%) -- 34% chance to 3HKO
You can easily set up Iron Defense and win 1v1 with Rest; this is a
counter by definition.
2. Banded Kleavor with Stone Edge is a
not a check to Gourging Fire:
252 Atk Gouging Fire Flare Blitz vs. 0 HP / 0 Def Kleavor: 187-222 (66.5 - 79%) -- 31.3% chance to OHKO after Stealth Rock
252 Atk Choice Band Kleavor Stone Edge vs. 0 HP / 0 Def Gouging Fire: 428-506 (121.9 - 144.1%) -- guaranteed OHKO
It wins 1v1 the majority of the time, but not under the worst case scenario it is a
not a check by definition (sorry Chait!).
3. Cutsap Heracross is a
check to non-Bulwark Gourging Fire:
Stated above; assuming a free switch it can come in and trade.
Even with 252 HP evs, gouging fire takes 23% recoil from flare blitz. This means:
252+ Atk Heracross Reversal (200 BP) vs. 252 HP / 0 Def Gouging Fire: 297-349 (71.7 - 84.2%) -- guaranteed 2HKO
is generally enough to kill. Variants with raging fury are locked into it, so you can click endeavor against those and easily revenge kill with any priority move. Regardless it wins 1v1 so it is a
check by definition.
I don't understand how you can say some of these sets, like Araquanid and Heracross, "Are not checks" when they
are by definition, unless you do not know what the definition of a check actually is.