With its critical hit ratio, coverage with Electric and Ice, and paralysis support, Starmie is too useful to not keep it healthy with Recover. If an enemy gets frozen or fully paralyzed, you're open to heal up before switching or continue attacking. Hydro Pump's only notable trait, really, is OHKOing Rhydon/Golem and having a chance to 2HKO Tauros. It won't reliably 2HKO any of the special sweepers, who can potentially paralyze you, and Tauros shouldn't be switching into Starmie anyway. Of course, critical hits with Hydro Pump are always good, but seeing how Blizzard is more accurate and has the freezing chance, you're more likely to be using that anyways. If not, then your best bet at that point would be to just switch out. How I see it, anyways.
Ok thanks for the explanation. Because I have less experience, I guess, my Starmie often doesn't have time to use recover, so as you said the occasional power boost hydro-pump brings to the table seems more appealing to me.
Starmie is mostly a defensive mon (albeit one that defends actively by actually threatening things with Super-Effective moves), and as such it really should use Recover. It's not breaking any Chanseys anytime soon, and it needs Recover for sticking around against Golem/Rhydon, Tauros, Mega Drain Egg, and Snorlax, stalling opposing Zam and Jynx, healing off Lapras/Starmie/Gengar Tbolts, etc...
I mean I guess non-Recover can work to try to alleviate Starmie's 4mss, but it's a gimmick at best since Recover is so useful.
Basically, because Lapras (STAB Blizzard + 130/80/95 bulk) and/or Slowbro (Amnesia + 95/110/80 bulk) are better than a Starmie without Recover. If you're getting good results with Recoverless Starmie, it's probably because people assume it has Recover.
They do different things. Lugia is an unbreakable wall, Snorlax is a more powerful offensive threat. Granted, in Ubers, Snorlax isn't nearly as scary as it is in OU, and a big reason for that is Lugia.
Regardless, Lugia is not in contention for GSC's #1 because implicit in that statement is that you're only considering the GSC OU tier.
Substitute/Focus Punch/Crunch/Thunderbolt, I guess you can go for HP Grass to deal with Pert. 252 HP/loads of SAtk /a bit of Spd to outspeed... stuff I can't recall. I suppose Quiet nature with 24/28 spd.
and yes when STalk picks Rest, the sleep count reset to 2.
Indeed. The rollover's only possible from an item boost, though, so only Marowak needs to worry about it (Pikachu could also rollover with a Light Ball, but it doesn't have Growth to boost its SpA that high in the first place - also, hardly anyone runs Pikachu anyway).