so i herd u talkin bout dem heliolisk in the viability rankings
Don't use:
Heliolisk @ Life Orb / Choice Specs
Ability: Dry Skin
EVs: 252 SAtk / 4 SDef / 252 Spe
Timid / Modest Nature
- Volt Switch / Thunderbolt
- Surf
- Grass Knot
- Focus Blast / Volt Switch
Heliolisk may be appealing with that base 109 Speed and nullifying Water-type attacks, but that's all it can ever do. 109 Speed is still slow when you have threats like Ice Beam Greninja, Focus Blast Gengar, Talonflame, Mega Pinsir, DD Mega Charizard X, Kyurem-B, Lati@s, ScarfExca, ScarfTTar, ScarfChomp, ScarfTerrak, ScarfDiggers, ScarfMamo, ScarfKeld, Rain Kingdra/Kabutops, and Scolipede threatening to take you out, and its bulk is like a piece of paper ready to be crumpled up. Heliolisk is also vulnerable to priority, meaning that Bisharp, Conkeldurr, and Breloom can revenge kill it easily. Also, Azumarill can opt to run CB or AV to get past it, and Gyarados will predict the switch in and DD or Sub. It also gets KO'd by Aegislash's Sacred Sword, and it fails the OHKO on Blade Form unless running Specs. It doesn't even get an option to cripple Mega Venusaur with, and it gets shut down by Chansey. Life Orb Heliolisk fails the 2HKO on SDef Heatran unless rocks are up.
Use this instead:
Thundurus @ Life Orb / Leftovers
Ability: Prankster
EVs: 252 SAtk / 4 SDef / 252 Spe
Timid Nature
- Thunderbolt
- Hidden Power Ice / Hidden Power Flying
- Thunder Wave / Nasty Plot
- Focus Blast / Taunt / Thunder Wave / Psychic / Substitute
OR
Manectric @ Manectite
Ability: Lightning Rod
EVs: 252 SAtk / 4 SDef / 252 Spe
Timid Nature
IVs: 2 Atk / 30 Def
- Thunderbolt
- Volt Switch
- Overheat
- Hidden Power Ice
OR
Raikou @ Choice Specs / Assault Vest / Leftovers / Life Orb
Ability: Pressure
EVs: 252 SAtk / 36 HP or SDef / 224 Spe
Timid Nature
IVs: 2 Atk / 30 Def
- Thunderbolt
- Volt Switch / Calm Mind
- Hidden Power Ice
- Shadow Ball / Extrasensory / Substitute
Really there is little reason to use Heliolisk over Manectric, Raikou, or Thundurus, who can do a lot more in the OU metagame. Thundurus is faster and can beat Lati@s and Gengar, which outspeed and destroy Heliolisk. It can also check flyspam with its higher physical bulk, as a Brave Bird fails the OHKO. Thundurus also has Prankster Thunder Wave, Taunt, and Nasty Plot to emergency check offensive mons, cripple stall, and set up a sweep, respectively. It has access to Psychic to dent Mega Venusaur and Amoonguss. It can even opt to run an anti-Defog set with Defiant to add to its unpredictability. Manectric is even faster and has access to Intimidate, allowing it to create a VolTurn core with Landorus-T. It also has Overheat to break through Aegislash and other Steel-types. Raikou has more offensive power, bulk, and Speed than Heliolisk, allowing it to break through defensive teams more easily, or run AV to serve as an offensive tank, or run a CM set and be a bulky sweeper while having Extrasensory for Mega Venusaur and Amoonguss. You get the point now. There is absolutely no reason to use Heliolisk in OU, as everything it accomplishes, something does it better.