Mantine is very underrated. It's 4x weakness to Electric make it easy to bring down with one hit, and he's supposed to be a very bulky Special Wall. However, with partner pokemon like Ground Types, Lightning Rod, and Volt Absorb pokemon, Mantine can have the uspport he needs to do his job.
For this post, I'll just list Mantine's special and best moves.
Confuse Ray/Swagger - Like just about every other pokemon, Mantine can Confuse and can be a bit dependant on confusion hax. Swagger gets special mention as it means Mantine can toy with special attacker opponents that stay in. It should also be noted that Swagger has potential in Doubles, which Mantine is very good at this gen.
Air Slash - A strange move for a Mantine to have, but notable nonetheless. Mantine has a usable 80 Sp.Atk stat, and allows him to deal with Grass types most other sets would have trouble with, especially Virizion. Also can be very haxy with the confusion moves above.
Aqua Ring - While not a very good move to rely on, unfortunately it's one of Mantine's few options at HP recovery. Mantine lacks Roost, so he'll need to depend on Leftovers; Aqua Ring can double your profits.
Hydro Pump/Surf - As said before, Mantine has a usable 80 Sp.Atk, so these moves are worth looking into. You know the drill, power vs. accuracy, but if you're using Mantine in Doubles, take extra consideration with the rest of your team.
Toxic - Like it or not, Mantine can do very little to other Water types. Air Slash and Ice Beam would solve any problems he'd have with Grass types, but only HP Electric is his best shot at Water types (and don't even think of mentioning Seed Bomb, with Mantine's poor 40 Atk). While pretty generic, Toxic allows Mantine a chance at besting most other Water types, only failing to hit the likes of Empoleon, Tentacruel, and Qwilfish, all of whom are vulnerable to Ground type moves, making Mantine extra viable in Doubles.
Hidden Power - As said before, Mantine has access to this move like all other pokemon, the only choice is what type to hit things with? Ground can be used to fend off Poison and Electric types, while Electric can hit other Water types. Don't think too hard on it, though, Mantine has other usable moves and only four moveslots.
Ice Beam/Blizzard - Like any Water type, Mantine gets Ice moves, to trump Dragon types with ease. Like with Hydro Pump and Surf, it's a matter of power vs accuracy. Neither get STAB, but Blizzard won't hit a teammate in Doubles. Tough choice.
Protect - What's a stall pokemon without Protect? A stupid one, I'll tell you. If Mantine's aim is to wait out on a dying opponent, then he needs this move. Always good to scout or stall Toxic damage.
Rain Dance - Mantine can set up weather, but he might have his fins full already with all of these moves to choose from. Besides, Mantine doesn't personally gain any benefit from it aside from boosted STAB.
Rest/Sleep Talk - Mantine regained the ability to use this combination in Black 2 and White 2, and his new egg moves? Err, Wide Guard and Amnesia. ...Regardless, this is Mantine best bet at restoring HP and status by himself, so it should be invested.
Scald - Arguably one of Mantine's best moves usable. This move should only be used for its status, the 80 BP with Mantine's 80 base Sp.Atk is a nifty bonus. The burns inflicted will cover Mantine's physical defenses like barnacles on a whale. Also Taunt proof, Scald should be your first choice when choosing an attack for Mantine.
Substitute - Always an option, but not so in Mantine's case, due to his lack of HP recovery. An Aqua Ring/Leftovers combo can cover him, and a Substitute is easy to set up on a special attacker lacking an Electric move. It also covers him for a switch, allowing you to Scald or Poison or Confuse the switch in before you yourself switch out.
Haze - Mantine doesn't use any boosting moves personally, so Haze is a very good option at bringing an opponent's stats back down to normal. Most special attackers won't hesitate to set up on a Mantine if possible, and Haze can cover for you while Mantine needs to do his own things.
Mud Sport - Now before you laugh, or you already did, Mud Sport is permanent while Mantine is on the field, and turns his 4x weakness to Electric into a 2x weakness. Factoring in Mantine's enormous 140 base Sp.Def, this is a significant resistance buff, and stays for as long as Mantine is in. It can also be used in Doubles to cover other pokemon; not sure if it stacks though...
Mirror Coat - Mantine's HP isn't that big, but his massive Sp.Def can help him abuse Mirror Coat. Slap on a Wacan Berry and Mantine can get rid of a troubling Electric type with ease. In case you blow Mirror Coat too early and your opponent starts setting up, Haze in an option to have on the side just in case.
Wide Guard - Only usable in Doubles, but it's hella handy. While Mantine can breathe easy with a Lightning Rod partner, it won't protect him from a Discharge attack, which are very common in that mode. Wide Guard can block it, and friendly Discharges as well, and even Explosion. The only catch is it'll block a teammates Surf and prevent you from getting a drink with Water Absorb.
Helping Hand - One of Mantine's new attacks in B2/W2, strengthening Mantine's place in Doubles. His main niche is spamming this move while a teammate fires either Earthquake or Surf, both of which Mantine is immune to. His huge Sp.Def also allows him to live through some Lava Plumes and survive enemy fire. Running Aqua Ring and Substitute will make Mantine very annoying to deal with.
Icy Wind/Tailwind/String Shot - More moves to give Mantine ground in Doubles. both moves are very good and should be considered depending on what else you're running. Icy Wind is Taunt proof, and lowers the stats of two opponents, allowing you to outrun them. Tailwind is a little more permanent, cannot be removed or nullified by Phazing, or in Mantine's case Hazing, and boosts a teammate's speed as well. The choice is up to you. (String Shot is only mentioned because it's terrible. It has both of Icy Wind's and Tailwind's negatives rolled into one move. It's vulnerable to Taunt, but at least it hits two opponents...)
Captivate - While ordinarily a bad move, be aware that people are still setting their pokemon's genders to female because of Rivalry beasts like Haxorus. A gender based meta, while hilarious, can give Mantine a gimmicky niche with Captivate, allowing him to survive most deadly special moves. It also hits two pokemon as well.
Mud Slap - This is the last move we're ending this list with. Still gimmicky, but nobody likes having their accuracy dropped. It's taunt proof and can provide haxy lulz as your opponent is trying to zap Mantine with Electric moves and you're just their, slapping mud, hiding behind subs, while they're dying from poison.
Mantine has loads of options, even more so in Doubles. While Mantine profits a bit more from offensive sets, that's because of the abundance of Electric moves. Since Gyarados, no one builds a team without an electric move, but if you can take out that factor, or deal with it, Mantine can have an easier time taking up the defensive role.
