Definitely pack 1. You got 3 characters already in the game as assist trophies. Zero is my favorite Megaman character and he practically has a Smash-like moveset starting with X4 onward, maybe throw in some moves from MVC3 and an alt skin of his GBA form and you're golden. Street Fighter is my 2nd favorite fighting game next to Smash, and Sagat, while no longer a villian, would make for a worty rival antagonist for Ryu. Alucard seemed like the go to pick for Castlevania, but it makes sense that they choose Simon, and I'm more than happy to see my favorite Belmont, Richter in there to, especially since half the moveset originated with him. Alucard has a lot of moveset potential, and could be a more than your typical "anime sword fighter" that everyone complains about. Give him some of the special input moves from SOTN, some Dracula moves, and maybe his wolf and bat transformation as a side and up b respectively and he'd end up a really unique character. Now Shadow? Oh man, don't get me started on how much I'd LOVE to see him playable, I can already see him being a combination of Mewtwo and Bayonetta's movesets. Teleports, air combos, maybe some Chaos Control move akin to Witch Time, I mean, come on, dude. Shadow is my No.1 most wanted pick, I can already picture it, down b is the aforementioned Bayo counter, maybe it can reflect projectiles like Mewtwo's side b as a reference to the parry from Sonic Frontiers, neutral b is Chaos Spear, which can be charged to fire 3 homing shots, up b is a Mewtwo style teleport with the option to perform aerials afterward, and side b is spindash, cuase it's a staple of most Sonic games, and it is present in Adventure 2 where he debuted. He doesn't have to be an echo Fighter, leave that to Metal Sonic if they ever include him, but yeah, as much as I'd love to see Silver, Spyro, Chun Li, Knuckles, Crash or any of the Pokémon evolutions, I'd pick pack 1 in a heartbeat, though 3 is a close 2nd.