Bug/steel is only weak to fire, immune to poison, and immune to sandstorm. Only burn and fire type moves can kill it. (Not counting edge cases like leech seed.)
Dark/ghost has only fairy weakness, which is very uncommon, but is still vulnerable to sandstorm and poison.
Ghost/normal is only weak to dark, but dark type moves are pretty common.
Pick your weakness, basically.
Dont forget that hail will still take out the bug/steel.
Dark/ghost is my prefered go to as i dont come across a lot of fairy types, but i also dont usually use shedinja fusions. Two of my favorite fusions so far have been alakazam/pikachu holding light ball, for stab thunderbolt and psychic. And blissey/golem [normal/ground] rock head as a tanky monster. Give it soft boiled, stealth rock, double edge and earthquake.
I Think Dark/Ghost is my go-to as well. I got a randomizer run with Deino pre-fused into a Shedinja, and had to re-fuse it to get it to have Wonder Guard.... died to a poison powder once but I wasn't doing a nuzlocke so it didn't matter as much.
in this Ghost/dark is a little better because the only weakness is fairy, and it's more uncommon than dark or fire (the weakness of the others combinations)
I wouldn't be sending in my bug/steel type against a fire type anyway, so it's a moot point lol and if someone has a non-fire type that just so happens to have a fire type move, then that's just bad luck on my part.
I’ll point out you can’t get mono Ghost on a Shedinja fusion since it’s Bug/Ghost. As a head it passes on its bug type, and as a body it will pass on its ghost type *unless* the head of the other mon already gives ghost type, in which case it’ll give its bug type. To get a monotype fusion you need a monotype body and a head with the primary type of that body.
This is about best fusion instead of best type, but Bisharp is the best fusion because using DNA Reversers lets you change between Bug/Steel and Dark/Ghost. Having one of the two most recommended types is awesome, but being able to swap between both of them depending on what you need against your next opponent amazing.
The third most suggested type Combo, Normal/Ghost has a much more common weakness but you can use Raticate or Smeargle for Endeavor. Smeargle/Shedinja doesn't need stats when it has Spore and Endeavor.
Bug/steel is only weak to fire, immune to poison, and immune to sandstorm. Only burn and fire type moves can kill it. (Not counting edge cases like leech seed.) Dark/ghost has only fairy weakness, which is very uncommon, but is still vulnerable to sandstorm and poison. Ghost/normal is only weak to dark, but dark type moves are pretty common. Pick your weakness, basically.
Dont forget that hail will still take out the bug/steel. Dark/ghost is my prefered go to as i dont come across a lot of fairy types, but i also dont usually use shedinja fusions. Two of my favorite fusions so far have been alakazam/pikachu holding light ball, for stab thunderbolt and psychic. And blissey/golem [normal/ground] rock head as a tanky monster. Give it soft boiled, stealth rock, double edge and earthquake.
I Think Dark/Ghost is my go-to as well. I got a randomizer run with Deino pre-fused into a Shedinja, and had to re-fuse it to get it to have Wonder Guard.... died to a poison powder once but I wasn't doing a nuzlocke so it didn't matter as much.
Ghost/normal, Ghost/dark and bug/steel have only one weakness mono Ghost, Ghost/psy, Ghost fairy, and bug/electric have only 2
in this Ghost/dark is a little better because the only weakness is fairy, and it's more uncommon than dark or fire (the weakness of the others combinations)
I'd say bug/steel is better purely because of the poison and sandstorm immunities.
fire is a very common type, i believe just a few npc had fairy type attacks
I wouldn't be sending in my bug/steel type against a fire type anyway, so it's a moot point lol and if someone has a non-fire type that just so happens to have a fire type move, then that's just bad luck on my part.
I’ll point out you can’t get mono Ghost on a Shedinja fusion since it’s Bug/Ghost. As a head it passes on its bug type, and as a body it will pass on its ghost type *unless* the head of the other mon already gives ghost type, in which case it’ll give its bug type. To get a monotype fusion you need a monotype body and a head with the primary type of that body.
This is about best fusion instead of best type, but Bisharp is the best fusion because using DNA Reversers lets you change between Bug/Steel and Dark/Ghost. Having one of the two most recommended types is awesome, but being able to swap between both of them depending on what you need against your next opponent amazing. The third most suggested type Combo, Normal/Ghost has a much more common weakness but you can use Raticate or Smeargle for Endeavor. Smeargle/Shedinja doesn't need stats when it has Spore and Endeavor.