Anti-Heatran set Mantine
(this was made as I was looking for a good counter to most Heatran set. Since Heatran is now the most common Pokemon in the metagame, teams have to be prepared)
Mantine has awesome Special Defences and fairly good typing. It loses to some common types like Rock (although most Rock moves are physical, so it would be silly to keep Mantine in then) and Electric. It has a weak movepool, and without a reliable recovery move it requires team support to work. However I think there is a place for it in the OU metagame.
Mantine @ Leftovers
Calm
Water Absorb
EVs: 252 Hp; 36 Def; 20 SpA; 200 SpD
~ Rest
~ Toxic
~ Ice Beam
~ Surf
This set requires a bit of help to function in more ways than just as a wall to Heatran. Rest is there to get rid of nasty status' (particularly Toxic), and Toxic is always a good move for a wall, and allows Mantine to do damage to whatever switches into Mantine once they realise Tran isn't going to hurt it. Mantine can break all Heatran subs with Surf, while a standard Scarfed Rash Heatran with max SpeA does less than 1/4 damage with Fire Blast. A Hidden Power Electric will do 70% max, allowing Mantine to just survive after SR damage - but that's uncommon from my experience.
How to best utilise this set?
- I've had a good bit of success using this Mantine with a core of Heatran and Shaymin, but Celebi could also work well. The idea is that Mantine attracts electric attacks, so Shaymin can get a fairly safe switch. If Mantine rests, switch out and try and find space for an Aromatheropy. All super effective moves directed at Heatran are soaked up by Mantine - and all of Shaymin's weaknesses are covered by Heatran and Mantine.
One thing stopping Mantine from being a more used Pokemon is a lack of real options in terms of moveset, and takes 25% from Stealth Rock. Therefore its better to have a rapid spinner or a lead that can outright prevent SR (the former is a lot easier). Ground spinners are great with Mantine, Claydol and Donphan in particular. These two can take the electric and rock types aimed at Mantine well.
Using NU and UU Pokemon in OU often requires a lot of team support instead of being an inferior substitute for something else (e.g. Mantine is an inferior special wall to Blissey). But with the right team support, Mantine is a perfectly usable player in OU, and I've had a fair deal of success with it in my current team. Heatrans that are running around these days usually don't have HP Electric, meaning that he can't hurt Mantine outside of explosion. It can support against other special sweepers and can take any neutral special move well.
I can't finish without mentioning Mantine's ability - water absorb. On a predicted water type attack, Mantine can recover itself. This makes him a great Pokemon against other Bulky Water types (without Sub), like Swampert and Vaporeon. Mantine can come in, and throw a Toxic at them, and rest if they do the same back.
It's not massively different to other Mantine sets (as it doesn't have a host of viable options) but this is to show that he is usable in OU.
I think the Big Blue Blissey as I call him is well worth a shot in OU, and not just on Rain Dance teams.