What I mean by "gatekeeper" list, is a list that you test your potential competitive builds against on your kitchen table. I ususally have one solid, easy to play build ready that any build I´m working on has to get through (in a solitaire match) to get a chance at the store.

Sometimes the "gatekeeper" build becomes the competitive build if it´s tough enough. Chewie/Leebo was a "gatekeeper" build of mine that simply beat all my more creative builds. I ended up using it in a local league and went 7-0 with it.

I guess Chewie is my "easy-mode" pilot because my current "gatekeeper" build includes good, old Chewie:

Chewbacca/Predator/C3PO/Luke/title/EU 60pts

Lothal Rebel/FCS/AutoBlasterTurr/Hera 40 pts

My Han/Corran build and/or my Jan/Wedge/Poe build. Both have proven very good for me in the field, so they are my bench marks.

I've done this in other games, and it's a great way to playtest out ideas. I haven't done so in X-Wing yet, but it's on my to-do list.

Mine is Omega leader w/juke and comm relay

Zeta leader with wired and weapons guidance

Wampa

3x academy pilot

Mine Is my last list I took to a store tournament. That way I get an idea of if I should place better or worse.

So mine is ....

Tie adv

Vader

LW, EU, title, ATC

Gamma vet x2

Deadeye, munititons, proton torps and bomds, chips.

I don't have specific gatekeeper lists. I ponder the specific ships that can ruin your day.

Any X7 Defender
Omega Leader
Whisper
Jake Ferrell
Dash Rendar / PTL / Kanan / Engine / HLC
Asajj Ventress / PTL / Latts Razzi
IG-88

I test it against Thugs and U boats.

backstabber
Academy pilot x5
OMG + Vader + Collision detector

Mine is

Howlrunner

3x blackcrack

Inquisitor

When I kitchen table the list I set dails on my new list then pick 2-3 sensible manouvers for each gatekeeper ships and then roll a dice to randomize which sensible manouvers to set.

The bonus is you get to learn two lists at once.

All the meta crap: Dengaroo, 3Jump, Palp Aces

My current three:

Tripple Scouts

Palp Aces

Dengaroo

Might need to add TLTs on that list, they starting to get popular again in my local meta.