You can invest in EV's in HP with a full 252, but it's more useful elsewhere since his HP is already pretty good.
Not sure how viable a modest Lanturn would work out when facing an Uber Pokemon on battle spot wi-fi or something, but it's probably worth a try if you're into the UU/NU tiers (:
Legendary pokémon are not allowed on rating battles, if he is going to do that he can run Lanturn;)
Most common pokémon:
252+ Atk Choice Band Talonflame Brave Bird vs. 196 HP / 0 Def Lanturn: 182-215 (41.3 - 48.8%) -- guaranteed 3HKO
252+ SpA Choice Specs Lanturn Volt Switch vs. 0 HP / 0 SpD Talonflame: 356-422 (119.8 - 142%) -- guaranteed OHKO
252+ SpA Altaria Draco Meteor vs. 196 HP / 0 SpD Lanturn: 195-231 (44.3 - 52.5%) -- 18.4% chance to 2HKO
252+ SpA Choice Specs Lanturn Ice Beam vs. 4 HP / 0 SpD Altaria: 436-516 (149.3 - 176.7%) -- guaranteed OHKO
192+ Atk Altaria Return vs. 196 HP / 0 Def Lanturn: 119-140 (27 - 31.8%) -- guaranteed 4HKO
192+ Atk Altaria Earthquake vs. 196 HP / 0 Def Lanturn: 232-274 (52.7 - 62.2%) -- guaranteed 2HKO
252+ SpA Choice Specs Lanturn Ice Beam vs. 64 HP / 0 SpD Altaria: 436-516 (142 - 168%) -- guaranteed OHKO
252+ Atk Huge Power Azumarill Play Rough vs. 196 HP / 0 Def Lanturn: 277-327 (62.9 - 74.3%) -- guaranteed 2HKO
252+ Atk Huge Power Azumarill Aqua Jet vs. 196 HP / 0 Def Lanturn: 62-73 (14 - 16.5%) -- possible 7HKO
252+ SpA Choice Specs Lanturn Volt Switch vs. 92 HP / 0 SpD Azumarill: 320-378 (87.9 - 103.8%) -- 25% chance to OHKO
Lanturn outspeeds most common used EV spread on Azumarill
0 Atk Gliscor Earthquake vs. 196 HP / 0 Def Lanturn: 320-378 (72.7 - 85.9%) -- guaranteed 2HKO
252+ SpA Choice Specs Lanturn Ice Beam vs. 252 HP / 0 SpD Gliscor: 576-680 (162.7 - 192%) -- guaranteed OHKO
He can't set up substitute when switched in to Lanturn and a Earthquake will not kill.
0 SpA Rotom-W Hydro Pump vs. 196 HP / 0 SpD Lanturn: 77-91 (17.5 - 20.6%) -- possible 5HKO
252+ SpA Choice Specs Lanturn Hidden Power Grass vs. 252 HP / 212+ SpD Rotom-W: 108-128 (35.5 - 42.1%) -- 85.8% chance to 3HKO after Leftovers recovery
252 SpA Life Orb Thundurus Focus Blast vs. 196 HP / 0 SpD Lanturn: 208-246 (47.2 - 55.9%) -- 78.5% chance to 2HKO
252+ SpA Choice Specs Lanturn Ice Beam vs. 0 HP / 0 SpD Thundurus: 272-322 (90.9 - 107.6%) -- 43.8% chance to OHKO
0- Atk Skarmory Brave Bird vs. 196 HP / 0 Def Lanturn: 75-88 (17 - 20%) -- possible 5HKO
252+ SpA Choice Specs Lanturn Volt Switch vs. 252 HP / 4 SpD Skarmory: 354-416 (105.9 - 124.5%) -- guaranteed OHKO
252 SpA Life Orb Starmie Psyshock vs. 196 HP / 0 Def Lanturn: 220-261 (50 - 59.3%) -- guaranteed 2HKO
252+ SpA Choice Specs Lanturn Volt Switch vs. 4 HP / 0 SpD Starmie: 306-360 (116.7 - 137.4%) -- guaranteed OHKO
252+ Atk Mega Scizor Knock Off (97.5 BP) vs. 196 HP / 0 Def Lanturn: 200-236 (45.4 - 53.6%) -- 41% chance to 2HKO
252+ Atk Technician Mega Scizor Bullet Punch vs. 196 HP / 0 Def Lanturn: 46-55 (10.4 - 12.5%) -- possible 8HKO
252+ Atk Mega Scizor Superpower vs. 196 HP / 0 Def Lanturn: 248-292 (56.3 - 66.3%) -- guaranteed 2HKO
252+ SpA Choice Specs Lanturn Scald vs. 0 HP / 4 SpD Mega Scizor: 151-178 (53.7 - 63.3%) -- guaranteed 2HKO
If Scizor packs super power Scizor wins, if not Lanturn can handle him
This are some examples I knew for sure it would win against, he can do very well in OU on the right team ofcourse. He will do better in UU/RU/NU but if you like something and want something, don't hold back and try it out! Just be carefull for ground and grass moves cause he can't live that.