Sorry about the title, it isn't working. Also sorry if I mess up the formatting, it's my first time :)
Pros:
Amazing power unboosted, ridiculous power after setup
Very good physical bulk
Almost perfect coverage with two moves
Good resistances to use
Powerful priority
Good abilities pre-mega
Great ability as mega
Cons:
Fairly low special bulk
Weak to common special moves
The pokemon it fares worst against are incredibly common
Stealth rock weakness, becomes 4x after mega evo, making it difficult to use early game
Swords Dance
#########
Swords dance
Return
Quick attack
Earthquake
Ability: hyper cutter/mold breaker/moxie -----> aerilate
252 atk, 252 spe, 4 hp? ( not sure about sr number)
Jolly
Moves
Swords dance is a great boosting move that puts it attack through the roof
Return is a powerful stab that can ohko nearly every non resist after an sd,and even some resists
Quick attack is powerful priority, kos most genesect after rocks + 1 spike
Earthquake gives it coverage on every type that resists ground, leaving its coverage only resisted by things immune to ground and resist flying, like skarmory
Set details
Three usable abilities pre-mega
Moxie allows it to get to +3 in some scenarios, important for things like full health genesect
Hyper cutter lets it ignore intimidate users, which is useful, although they all die to +1 return
Mold breaker lets it beat rotom wash at plus 2 (and bronzong I guess)
Usage tips
Try not to use it until you think it can sweep or you really have to, it is weak to sr, and becomes weaker after the mega evo
If your premega ability is going to help, feel free to stay as regular pinsir! however your speed is much lower, so watch out for that
Many talonflames are slower, and a +2 quick attack ohkoes after rocks, but only do that in a time of desperation as it is quite risky
It can take almost any neutral hit, especially physical ones, and set up, even on strong things like cb azumarill locked into aqua jet
Team options
Deoxys d/s sets up hazards that are crucial for its quick attack against fast things and it's return against walls
Bisharp can take advantage of defog on those hazards, and cripple physical walls like skarmory who are forced to stay in and whirwhind the bisharp away, allowing pinsir to sweep
Rotom w can switch into many, if not all of pinsir's counters
Excadrill spins for it and can kill rotoms, which is important for pinsir
Other options
Close combat is the hardest it can hit skarmory or rotom wash, although neither hits hard enough to be worth it. Bulk up could be used to allow it to tank physical hits, but is almost entirely outclassed by swords dance. Things like substitute, x scizzor, double edge could be used, but it's main set is far and away the best set.
Checks and counters
Skarmory is the only true counter to mega pinsir. Rotom is a very solid check, although it has to be healthy. Thundurus I is a great check, although it can't switch into return plus sr plus quick attack, although it can leave pinsir with a nice little present with its prankster twave in that scenario. Talonflame, especially variants that outspeed is a greT check, although it can't switch in. Any electric type that outspeeds it checks it, such as mega manetric, raikou, or jolteon checks it, although they can't switch in. Scarfer that resist flying check it, such as heatran, tyranitar, or jirachi
Pros:
Amazing power unboosted, ridiculous power after setup
Very good physical bulk
Almost perfect coverage with two moves
Good resistances to use
Powerful priority
Good abilities pre-mega
Great ability as mega
Cons:
Fairly low special bulk
Weak to common special moves
The pokemon it fares worst against are incredibly common
Stealth rock weakness, becomes 4x after mega evo, making it difficult to use early game
Swords Dance
#########
Swords dance
Return
Quick attack
Earthquake
Ability: hyper cutter/mold breaker/moxie -----> aerilate
252 atk, 252 spe, 4 hp? ( not sure about sr number)
Jolly
Moves
Swords dance is a great boosting move that puts it attack through the roof
Return is a powerful stab that can ohko nearly every non resist after an sd,and even some resists
Quick attack is powerful priority, kos most genesect after rocks + 1 spike
Earthquake gives it coverage on every type that resists ground, leaving its coverage only resisted by things immune to ground and resist flying, like skarmory
Set details
Three usable abilities pre-mega
Moxie allows it to get to +3 in some scenarios, important for things like full health genesect
Hyper cutter lets it ignore intimidate users, which is useful, although they all die to +1 return
Mold breaker lets it beat rotom wash at plus 2 (and bronzong I guess)
Usage tips
Try not to use it until you think it can sweep or you really have to, it is weak to sr, and becomes weaker after the mega evo
If your premega ability is going to help, feel free to stay as regular pinsir! however your speed is much lower, so watch out for that
Many talonflames are slower, and a +2 quick attack ohkoes after rocks, but only do that in a time of desperation as it is quite risky
It can take almost any neutral hit, especially physical ones, and set up, even on strong things like cb azumarill locked into aqua jet
Team options
Deoxys d/s sets up hazards that are crucial for its quick attack against fast things and it's return against walls
Bisharp can take advantage of defog on those hazards, and cripple physical walls like skarmory who are forced to stay in and whirwhind the bisharp away, allowing pinsir to sweep
Rotom w can switch into many, if not all of pinsir's counters
Excadrill spins for it and can kill rotoms, which is important for pinsir
Other options
Close combat is the hardest it can hit skarmory or rotom wash, although neither hits hard enough to be worth it. Bulk up could be used to allow it to tank physical hits, but is almost entirely outclassed by swords dance. Things like substitute, x scizzor, double edge could be used, but it's main set is far and away the best set.
Checks and counters
Skarmory is the only true counter to mega pinsir. Rotom is a very solid check, although it has to be healthy. Thundurus I is a great check, although it can't switch into return plus sr plus quick attack, although it can leave pinsir with a nice little present with its prankster twave in that scenario. Talonflame, especially variants that outspeed is a greT check, although it can't switch in. Any electric type that outspeeds it checks it, such as mega manetric, raikou, or jolteon checks it, although they can't switch in. Scarfer that resist flying check it, such as heatran, tyranitar, or jirachi
