https://boards.fireden.net/v/thread/422333705/#422333705
Since someone partially leaked the game somewhat accurately here recently (not 100%, maybe to protect themselves) I'm going to shed some light on some details of the game. Feel free to ask any questions you might have ONLY on what's below.
1. Simon Belmont is indeed in the game. He fights on Dracula's Castle as his home stage, where Dracula is a stage hazard.
2. Instead of coin blaster and trophy rush, there is a mode called "Smash Lanes" which functions as a strange version of bowling. You earn more trophies by hitting pins with point multipliers, and every X amount of points the pins glow gold and are worth triple.
3. King K. Rool is also included as a playable character
4. There are unlockable costumes for every character - Dry Bowser and Meta Ridley are both unlockable costumes
5. Minecraft's Steve is an assist trophy
6. King Hippo is another brand new fighter - yes his pants fall down in a taunt
7. There are over 1,100 trophies total in the game to collect and view.
8. Smash Run returns with 3 different maps
9. There is a funny stage on a gigantic ROB where his arms move up and down
10. Adventure mode comes back in a style in-between melee and brawl, with some cutscenes and series-specific stages. Some are not represented, such as Ice Climbers and Duck Hunt.
11. There are three more echo fighters left to be revealed - Dark Samus, Shadow the Hedgehog, and Metal Mario
12. Metal Mario's N64 stage comes back along with N64 Kongo Jungle and N64 Peach's Castle. Brinstar and Sector Z do not return.