If your playing Quagsire in there you can 2HKO everything, even without the tool. And if they decide they need to get rid of it with Megashot...well you get a free tool placement. It's a bit tough since you can't really work with DREs since that'll sacrifice the 2HKO, but Scrambles work nice.
Besides that, if you can get a quick Wooper out to Amnesia it's great. They either have to Megashot to KO or retreat, and if you're fast enough (Say, T2/T3) it's going to get in their way. Then all you gotta do is get something else ready ready, and if you do let them kill you...Scramble away. If you have the DRE, evolve into Quagsire, attach something and get ready for the KO.
Problem is Manectric is resistant to Kingler, so hopefully you can get a Quagsires out, which is great to reuse Mysterious Shards if you have the oppurtunity. Ideally, you want to start with a Wooper equipped with an Energy Root/Mysterious Shard/Cessation Crystal (For Mew).