A fair take, but I do sort of want to come to Musharna's defense for a second.
There is no denying that Musharna is absolute ass, its attacks is by far one of the most absolutely terrible in the entire game and easily among the worst pokémon in pokémon conquest by far. But I really would not call it the worst in-game pokémon of all time, im pretty sure there must be a mon in a sidegame or something that must be just as bad, and its competition in conquest is actually quite fierce for worst pokémon of all game.
First, lets talk about the main thing that makes Conquest different from the main game: The map. Your pokémon aren't just fighting tools, you move them across the map and in many maps your objective isn't just to kill pokémon; its to also archieve the objectives in the map. There are two main modes: simple battle and flag battle. For simple battle, sure, Musharna is one of the worst possible options to bring in the entire game.
For flag battles however, Musharna is actually quite a decent sponge for the flag map. Flag battle maps require you to capture and protect flags. This often means that you have to leave a mon behind to capture the flags, which put you in a specific spot in the map. This is hell for a ton of mons, since its practically impossible for a lot of them to fight their attackers due to bullshit move conditions. Look at Ampharos and Luxray, the two are stuck with the abysmally dogshit thunder, meaning that unless their opponent is exactly 3 squares away in a straight line, and given most mons attack either in front of them or two squares awyas make them sitting ducks.
Musharna meanwhile is not only extremely fat, with a high hp stat and defenses, but the passive healing of the flag means you can tank a lot of hits. Combine that with the passive ability to put things to sleep and I can assure you Musharna can flag defend more than 60% of the game's entire mon selection.
Hell, If you wanna use it in a defense map, Musharna can be used like a fucking asshole. Range 3 speed is good enough to put enough distance between you and invaders, allowing you to outrun an invading mon that the game deemed would be enough to beat you, and if they try to catch you getting sleeped as you run makes it even harder to be caught. Get yourself somewhere like Avia or the ice map and you are never getting caught.
Here's examples of mons I actually think to be the absolute worst in the game in conquest, whose strength is almost as bad as musharna:
Rhyperior: 2 range speed is horrifically terrible for when you are facing a map, but combine that with a 3 tile attack that can't hit anything in the squares in the middle, that can't be fired on repeat, and a double weakness to grass and water attacks, and if this isn't the actual worst mon in the game its by far the most obnoxious one.
Ampharos and Luxray: Have fun hitting that 3 tile thunder, oh and have fun being helpless against ground, grass, dragon and electric types anyways.
Forretress: Excellent in defense, your primary is doing so little damage however it might as well do less damage than Musharna in a game.
Gothitelle: Two tile attack with a huge range, but can fire on repeat and its very likely your opponent escapes or heals itself enough in the two turn it takes for it to hit. Hope you had enough turns left buddy!
Hell, id argue having 3 range movement makes it automatically a hardcounter to anything stuck with 2, even something like zard is near imposible to get moving since it has 2 tiles of movement and can't use shortcuts.
