Maushold is an interesting Gimmick Pokémon, from its evolution method (it can literally evolve offscreen [no one knows where the new mouse came from]) to its signature attacks. Fun Fact, the Japanese name of Population Bomb is nezumizan, which roughly translates to "mouse math" or alternatively "mouse cut" hence why the move does get boosted by Sharpness. Admittedly as useful as knowing that Mega Launcher buffs the power of Kyogre's Origin Pulse, but it is there.
What is more useful is Maushold's utility in doubles. While Technician Poopulation Bomb is still very much a house even in Doubles, what is of even more importance Maushold's access to Friend Guard. A passive 25% damage reduction that stacks with screens is amazing and Maushold is the first Fully Evolved Pokémon to have this ability. And while yes, Maushold's durability leaves a lot to be desired, being frailer than Eviolite Clefairy (who is admittedly, not available), it makes up for that in spades by not being beholden to Eviolite and having actual offensive presence on the field as opposed to Clefairy's pure passivity. And its not just Friend Guard that catapults Maushold to the spotlight. Having amazing moves in its arsenal including Encore, Feint, Follow Me and Helping Hand is amazing for Doubles, and that is not even getting into strategies like Beat Up Annihilape. While Maushold's durability still leaves a lot to be desired, the support and disruption it provides is invaluable.
Fight Together, Stay Together
Maushold
Ability: Friend Guard
Item: Wide Lens
-Follow Me
-Encore
-Protect
-Population Bomb
EVs and Nature:
4 HP /252 Atk / 252 Spe
Jolly Nature (+Spe, -SAtk)
Doubles set aiming to support and disrupt. Follow Me is great for this set -most supporter Pokémon, including Maushold are fairly passive, so redirecting attacks away from Maushold's pressure applying partner is worth its weight in gold. Encore is brilliant disruption in VGC. Double Battles have tons of moves that do anywhere from nothing to actively detrimental if forced to be repeated, up to, but not limited to Fake Out, Protect, Detect, weather, screens, Tailwind, and Trick Room (admittedly that one is hard to get with Encore). Protect is also invaluable, punishing opponents who want to shutdown Friend Guard early. Population Bomb rounds out the set -even without Technician it still hits appreciably hard and does prevent Maushold from being completely passive.
Other Options
Beat Up -If running with Annihilape, Beat Up is mandatory getting 4 hits onto Annihilape pumping Rage Fist up to a terrifying Base 250 Power.
Feint -Punishing the best move in doubles is amazing. And Maushold can easily get this off if need be by locking an opponent into Protect with Encore.
Taunt -stop setup in its tracks. Also pairs well with Encore, forcing a switch or Struggle
Helping Hand -Buff Ally for big damage.
Super Fang -A lot of Pokémon are nowhere near as durable at half HP, especially when Maushold can't reach that threshold with its own attacks.