Yep, I was right.
Wildcarding tags returns a maximum of 20 tags
[*tag*] is the same as favouriting
[*tag*], so I performed a few searches and compared the results.
This is what I searched. I wasn't particularly interested in the results, just in generating the maximum amount of tags possible:
When searching or favouriting wildcards, the wildcard is 'expanded' into the search box. Here are the resulting search strings from the above searches:
[pokemon-go] or [pokemon-x-y] or [pokemon-series] or [pokemon-sun-moon] or [pokemon-sixth-generation] or [pokemon-omega-ruby-alpha-sapphire] or [pokemon-fifth-generation] or [pokemon-first-generation] or [pokemon-sword-shield] or [pokemon-fourth-generation] or [pokemon-heart-gold-soul-silver] or [pokemon-third-generation] or [pokemon-bank] or [pokemon-second-generation] or [pokemon-seventh-generation] or [pokemon-lets-go] or [pokemon-ruby-sapphire-emerald] or [pokemon-black-2-white-2] or [pokemon-diamond-pearl-platinum] or [pokemon-fire-red-leaf-green]
[sonic-mania] or [sonic-3-and-knuckles] or [sonic-and-sega-all-stars-racing] or [sonic-the-hedgehog] or [sonic-3] or [sonic-the-hedgehog-series] or [mario-sonic-london-2012] or [sonic-and-knuckles] or [sonic-all-stars-racing-transformed] or [sonic-generations] or [sonic-the-hedgehog-2006] or [sonic-the-hedgehog-4-episode-1] or [team-sonic-racing] or [sonic-adventure-2-battle] or [sonic-cd] or [sonic-forces] or [sonic-generations-3ds] or [sonic-the-hedgehog-2] or [sonic-unleashed] or [sonic-rivals]
[borderlands-2] or [borderlands] or [bloodborne] or [skyrim-dragonborn] or [borderlands-pre-sequel] or [borderlands-3] or [borderlands-series] or [borderlands-2-tiny-tinas-assault] or [monster-hunter-world-iceborne] or [tales-from-the-borderlands] or [borderlands-goty-edition] or [borderlands-2-vr] or [battleborn] or [hello-neighbor] or [zombies-ate-my-neighbors] or [pvz-battle-for-neighborville] or [pokemon-reborn] or [harbormaster] or [final-fantasy-airborn-brigade] or [chaos-reborn]
[call-of-duty-modern-warfare-3] or [call-of-duty-black-ops] or [call-of-duty-black-ops-2] or [call-of-duty-modern-warfare-2] or [call-of-duty-ghosts] or [call-of-duty-4-modern-warfare] or [call-of-duty-black-ops-3] or [call-of-duty-advanced-warfare] or [call-of-duty-world-at-war] or [call-of-duty-series] or [call-of-duty-ww2] or [call-of-duty-infinite-warfare] or [call-of-duty-black-ops-4] or [call-of-duty-united-offensive] or [call-of-duty-elite] or [call-of-duty-modern-warfare] or [call-of-duty] or [call-of-juarez-gunslinger] or [theatrhythm-curtain-call] or [call-of-cthulhu-dcote]
[simcity-2013] or [sims-3] or [euro-truck-simulator-2] or [simcity-4] or [sims-4] or [pewdiepie-tuber-simulator] or [sims-2] or [simcity-buildit] or [american-truck-simulator] or [simpsons-tapped-out] or [goat-simulator] or [flight-simulator-x] or [the-sims] or [the-sims-freeplay] or [cultist-simulator] or [surgeon-simulator-2013] or [farming-simulator-2015] or [farming-simulator-2013] or [sims-medieval] or [artemis-spaceship-bridge-simulator]
[the-elder-scrolls-5-skyrim] or [grand-theft-auto-5] or [star-wars-the-old-republic] or [grand-theft-auto-online] or [the-witcher-3] or [minecraft-feed-the-beast] or [zelda-breath-of-the-wild] or [the-witcher-2] or [metal-gear-solid-5-the-phantom-pain] or [the-elder-scrolls-online] or [the-binding-of-isaac] or [the-binding-of-isaac-rebirth] or [saints-row-the-third] or [heroes-of-the-storm] or [the-elder-scrolls-4-oblivion] or [the-secret-world] or [grand-theft-auto-4] or [grand-theft-auto-san-andreas] or [realm-of-the-mad-god] or [the-elder-scrolls-3-morrowind]
[minecraft-commands] or [borderlands-2] or [grand-theft-auto-5] or [grand-theft-auto-online] or [android] or [candy-box-2] or [borderlands] or [civilization-5-gods-and-kings] or [grand-theft-auto-4] or [might-and-magic-heroes-6] or [mount-and-blade-warband] or [dead-island] or [grand-theft-auto-san-andreas] or [mass-effect-andromeda] or [borderlands-pre-sequel] or [candy-box] or [candy-crush-saga] or [rock-band-3] or [skylanders] or [wasteland-2]
At first I thought it might be a character limit, but the search box actually has a lower text limit than what is returned when searching with wildcards. (try searching with a broad wildcard then delete a character or two and attempt to add another character. You can't do it).
Then I decided to count tags or more specifically, instances of the word
or (including the spaces around it). Here's the results:
With 19 'or's, that means the wildcard functionality is limited to returning the first 20 tags it finds. i.e.
[tag-1] or [tag-2] → 1 'or', 2 tags
[tag-1] or [tag-2] or [tag-3] → 2 'or', 3 tags
[tag-1] or [tag-2]... or [tag-n] →
Suffice to say, if you want to ensure all Pokemon tags are favourited, you might want to consider refining your wildcards, splitting them into 2 or more separate favourite groups.