Volt Absorb always to screw with Manectric, Thundurus, Zapdos, Rotom-W and other electrics. One of the few niches it has over Rotom really since those guys can still use their STABs on Rotom-W. Water Absorb could be fun for screwing over Water stallers which rely on Scald + burn damage I suppose but Lanturn's already resistant to Water to not mind taking Water attacks.
I have a few Lanturns which I switch around. The defensive ones which I've had the most success with have either Thunderwave, Discharge, Scald, Heal Bell or Ice Beam. I've run an offensive set with Dazzling Gleam, Surf, Thunderbolt and Ice Beam but Lanturn's not really a powerhouse. I run Calm on the defensive ones with 252Def/200SpD/56HP I think since the HP is already huge enough to not require much investment.
Soak is pretty gimmicky but Lanturn's a bit slow to use it effectively, plus the opponent can simply switch out. Haven't tried stall sets utilizing Stockpile, Aqua Ring and Toxic so can't comment on that, though Confuse Ray is fun to have around and very spammable if the opponent doesn't have Magic Bounce.
