READ BELOW IF YOU ARE CURIOUS ABOUT THE MECHANICS OF EACH HERO
Each hero had a different ultimate that was made to fit the character.
For instance, Celestia's ultimate caused explosions to appear around the members of the opposing team. Such explosions were merely aesthetic, the real effect her ultimate had was a steady drain of HP which stopped at 1HP. So if such team had no medics they were instantly steamrolled. Also, she only had a melee weapon but I don't remember which.
Luna was a carbon copy of Celestia, the only difference was the music that played during her ultimate.
Applejack's character had a similar function to the Engineer. She had a wrench and could build the same things a normal Engineer could, and due to that fact alone, she was simply the best defensive hero of that gamemode. Her buffed health plus the functions and capabilities of a normal engineer were extremely powerfull on defense. I remember her ultimate frequently causing alot of rage which was expressed via voice or normal chat. It spawned lots of crates with minisentries on top of them in random positions close to teammates, which completely nulified 90% of pushes made by the enemy team.
Rainbow Dash's character had a similar function to the Scout, she also had a ridiculous amount of double jumps, which were around 20 if I'm not mistaken. A good RD player could be offensive and rush a team VIP like a Medic, kill him and get out without losing too much HP due to her mobility and double jumps. Her ultimate caused a rainbow to expand outwards from the position in which she activated it. It caused her and her teammates to become 1.5x faster than normal, and also caused a rainbow trail to appear from behind her and her teammates as they moved during the ultimate.I also think that RD's team had their firing rate increased as well but I don't remember so I can't confirm that fact. Her weapon was The Sandman, a Scout melee.
Fluttershy was one of the most overpowered and often the most frequently picked hero. She played like the Medic and had a Medigun and a Bonesaw as weapons. The fact that she had more health than normal Medics meant that her team was constantly being healed and since she usually sat behind her teammates she was at a low risk of being killed compared to other heroes, and if that wasn't enough her uber provided invulnerability and critical hits to her target. But that's not even the most ridiculous part. Her ultimate caused EVERYONE on her team to be constantly healed without her intervention to the point of being overhealed (1.5x the normal HP of a class). It pretty much guaranteed the capture of a point in most cases.
Pinkie Pie played like the Soldier, she had a normal Shovel as a melee weapon and had the best DPS out of all the heroes due to her ultimate. Her ultimate gave her a Rocket Launcher with permanent crits that had a retarded blast radious and ridiculous damage, It didn't matter if you were a overhealed Heavy, you would still die. I remember instances where a player used Pinkies ultimate on a large cluster of enemies, the killfeed basically lit up instantly and her team proceeded to win the match. The only notable downside was her ammo count which was only 2 clips of 6 rockets each if I remember correctly.
Rarity played like the Spy, but the only weapons she had were a regular Knife, so she couldn't destroy sentries with sappers and couldn't disguise, but she still could become invisible at will. Her ultimate caused the enemies to become temporarily scared, which made it so they moved at half their regular speed and coudnt't attack. This effect was also applied to the enemy sentry guns, but the downside was that if the enemy or buildings weren't close to her, the desired effect didn't happen.
Twilight Sparkle played like the Soldier, her weapons were a regular Shovel and a Cow Mangler with infinite ammo. I wish I could tell you but I don't remember the mechanics of her ultimate.
Chrysalis played like the Spy, much like Rarity. I also don't remember how her ultimate worked but I can tell you that she couldn't cloak like Rarity but her main weapon, Your Eternal Reward, a Spy knife, allowed her to disguise as her victim uppon sucessfull backstab. It fit her pretty well.
Vinyl Scratch played like the Soldier. She had a melee weapon which was a normal Shovel and a primary weapon which was a Black Box, (rocket launcher) which did 1 damage to enemies but had considerable knockback. It served more as an harassment tool than anything else. Unfortunatly I don't remember how her ultimate worked.
Octavia played like the Medic, but only had one melee weapon, The Amputator, so she couldn't heal like Fluttershy. I also don't remember how her ultimate worked. Fun fact: when the Medic taunts with the Amputator he performs a motion which imitates a person playing the violin, which heals nearby allies. That's the reason that weapon was chosen for Octavia.
Lyra also existed as an available hero but I can't remember anything about her weapons or abilities.
Bon Bon was also there, but I also don't remember anything about her.
I will add to this post in the future if I remember anything else about this mode.