Steelium Heatran:
Heatran @ Steelium Z
Ability: Flash Fire
EVs: 4 Def / 252 SpA / 252 Spe
Modest Nature
IVs: 0 Atk
- Magma Storm
- Earth Power
- Steel Beam
- Taunt / Stealth Rock / Toxic
When i saw Grassium tran being suggested, i knew i had to talk about steelium Steel Beam Heatran, because i personally really prefer Steelium.
Steelium is very easily one of the strongest nukes in the tier, and of course almost entierly annihilate Tapu Fini:
252+ SpA Heatran Corkscrew Crash (200 BP) vs. 252 HP / 64 SpD Tapu Fini: 271-321 (78.7 - 93.3%) -- guaranteed 2HKO after Leftovers recovery
It quite literally hits everything that Grassium hits, except Gastrodon (both of which u could either abuse with teammates or just toxic), Slowking (which is kind of a fake check anyway - and pursuit trappable) and Mega-Swampert (which takes ton of damages from the Z move still, and has no form of recovery - 252+ SpA Heatran Corkscrew Crash (200 BP) vs. 0 HP / 0 SpD Swampert-Mega: 165-195 (48.3 - 57.1%) -- 91.8% chance to 2HKO ).
It just completly deal ridiculous damages to anything that doesn't resist it (often scoring the OHKO), notably other common Heatran switch ins that Grassium doesn't really hit, such as Garchomp, Kommo-O, or Mega-Latios.