A new theory after the addition of big mushrooms is to combine Gbaits + Mushrooms + Chef contest to have a larger chance to bait a 600 bst legend or UB. This is a reference list of themes, spawns and suggested leads. Themes without unique spawns I would suggest to not use gbaits. Abundant Shrine- landorus so use pure water Asia- jirachi landorus celesteela - Rotom-heat if you have one otherwise greninja looks solid. Brown- heatran landorus - Any water Cave- Diancie, Zygarde - Klefki Cerulean Cave- mew - Pure bug looks solid Daycare- Default- Desert- Dojo- marshadow - I would suggest a pure ghost Dragonspiral Tower- guzzlord - Pure bug Factory- genesect xurkitree - Hard one, either pure fire or maybe ground Fairy Tales- hoopa tapu lele - ghost seems good Forest- buzzwole celebi tapu bulu - Fairy type or a way to hit celebi like ghost. Fire/Flying also work but hit the entire theme Lake- Tapu fini - Nidoking/queen Meadow- shaymin meloetta - Pure Dark type or Weavile Mega Pokémon- Latios/Latias - Use scizor Mt. Pyre- darkrai necrozma - Either heracross or Fairy type Night- jirachi cresselia darkrai - Volcarona looks solid Normal- meloetta - Dark type Object- kartana - Use pure fire Parallels- Latios/Latias cresselia darkrai - Pure bug seems really good Ruins- magearna - Pure fire type Sea- manaphy - Grass type to avoid flying Sky- landorus tapu koko - Pure water or ground. Pure poison also good to hit the rest of the theme for neutral to catch. Physical- Quadrupeds- Snowflake- Space- jirachi deoxys cresselia - Chandelure seems solid Starter Pokémon- Tundra- Urban- victini hoopa pheromosa - Drifblim seems great. Krookodile if you want some rotoms Volcano- heatran volcanion nihilego Tricky. Ground type hits like the entire theme. Could use electric to hone in on volcanion. Weather - koko so ground? Updated thanks to LittleRoot
Cave - Diancie, Zygarde - Alolan Sandslash seems the best but Klefki would do good to. Fairy tales- Tapu Lele and Hoopa any pure ghost would be the best Forest- Tapu Bulu, Buzzwole- MOLTRES for Celebi use pure bug to avoid bulu and that mosquito. Lake- Tapu Fini , could use Nidoking to avoid flyings Sky - it's hard to bait both Lando and Koko using single mon (literally impossible) so pure poison for Koko I guess
Don't forget that Buzzwole spawns in Forest, and Pheromosa spawns in Urban. Oh and Tapu Koko is also in Weather It just kinda threw me off a little when I was viewing it the other day.
For themes that have only one possible 600 BST spawn, it won't be necessary to type-match it. That's because there won't be another 600 BST to compete for the spawn. You could use any type, and if a 600 BST "happens" to spawn, it will always be that exact one anyway.
I thought big mush avoids chef and type effectiveness. hmm what's best to get a Latias uh-uh? Well most of the safarians say so, abt big mush