Riolu ain't gonna be tanking any hits, so replace Eviolite with Focus Sash, which garuntees at least on Follow Me. However, Prankster doesn't help Follow Me at all because it already has +3 priority. There are many other, more capable Follow Me users, namely Clefable and Togekiss. Follow me is better used on bulky Pokémon, and those two fit the bill.
Clefable@ Leftovers
Ability: Magic Guard
EVs: 252 HP / 252 Def / 4 SDef
Bold Naturep
- Follow Me
- Moonblast
- Calm Mind
- Soft-Boiled
Magic Guard means no Toxic, hazards, and weather. EVs and nature buff Defence. Follow Me protects you teammate. Moonblast is STAB and prevents Clefable from being Taunt bait. Calm Mind boosts Sp. Defence for bulk and Sp. Atk to kill things with Moonblast. Soft-Boiled is recovery.
Togekiss@ Leftovers
Ability: Serene Grace
EVs: 252 HP / 240 SDef / 16 Spe
Calm Nature
- Follow Me
- Roost
- Thunder Wave/Tailwind/Dazzling Gleam/Air Slash
- Thunder Wave/Tailwind/Dazzling Gleam/Air Slash
EVs and nature offer special bulk. Follow Me is Follow Me. Roost is for extra recovery. Thunder Wave slows sweepers to make it easier for Togekiss' teammates to sweep, while Tailwind buffs your team's Speed. Dazzling Gleam is Fairy STAB and is a spread move, while Air Slash has a wonderful flinch chance and ParaFlinches with Thunder Wave.
So yeah, there are much better options than Riolu to use Follow Me, and since it already has priority Prankster is unneeded.
EDIT: Clefable also has access to Helping Hand via ORAS Move Tutor.
