Complete all the tasks to unlock Sonic the Hedgehog/russgamemaster.
1 - Eggman's robots
"Eggman is building larger robots than usual. Take them out!"
Defeat 25 Sentinels. Be careful, as some are more likely to critical hit ponies.
Reward - 2000 silver
2 - Step it up!
"You need to be fast to survive in my world."
Use 5 Chrono Boosts and 5 Chrono Accelerators. These can be randomly dropped by any enemy.
Reward - 10 CP
3 - The Rainbooms
"I've been compared to this Rainbow Dash a lot. Do those bronies really claim she's faster than me?"
Use Rainbow Dash's Sonic Rainboom 5 times. Sonic Rainboom is her third skill in her Scrapper mode.
Reward - 5 gold
4 - Chaos Emeralds
"Rarity can find gems. Maybe she can find the Chaos Emeralds so I can go super and save this world?"
Use Rarity's Sharp Pointy Gems and Gemstorm 5 times. These are her first and fourth skills, respectively.
Reward - 10 CP
5 - Ring Sword
"You need rings to survive in my world, too."
Research the Ring Sword.
Reward - The Ring Sword
6 - Train with Sonic
"And one more thing. Before I join your team, you need to be prepared and know what you're up against."
Complete all of Sonic's Simulator challenges.
Reward - 15 gold
Sonic simulator challenges
You play as Sonic in all of them.
1. 1 Slicer Thug, 1 Angler Thug, 1 Marauder
(special) High Crits - high chance to crit
(enemy) Pressure Points - causes either Weakened, Slowed, Dizzy, or Exposed.
(enemy) Wide-Open - takes extra damage from melee attacks
(self) Rings - heals teammates when attacked.