ok I admit bias, as this is a more personal answer, but when someone pulls out a charizard things are guaranteed to get hype. There are no major Charizard users, so nobody knows what he can do. Even when I play Zard and do things that are fundamental to Zard play, such as U-throws on a high platform, flare blitz snapping to ledge, or armoring through stuff with rock smash, people get really hyped, because they never see these things. But when a really good Zard main plays he can do some amazing things, like jab locking with a jump cancel reverse U-smash, or jab cancel into a variety of mix-ups, or hard punishing after reading just one airdodge, or footstool into rock smash combos! Those things get me so hyped!
I find falcon more hype than Ganon because of the faster pace of the match, and convoluted off stage play using wall jumps and up-Bs to extend the time they can fight in the air, until someone gets stomped. Also the occasional knee or falcon punch to take a stock are so hype.
I always loved to watch Greninja, but it wasn't until iStudying blew everyone away at BEAST that I really took an interest in the guy. Greninja has such a unique moveset, and can spike or jab lock in the most hype of ways. I think of Greninja as a more hype Pikachu, and Pikachu play is already pretty hype, especially with those edgeguards with Thunder, but Greninja is just a super fun, hype character to play and watch.
I miss Abadango's Pac. He is doing extremely well with Mewtwo now, so that's cool too, but Pac was just so interesting to watch! I love the pressure that Pac can apply when you've got a fire hydrant, spaceship, and lots of Fairs flying towards you, I love the tricks you can pull off with the various fruits, especially with Z-dropping and throwing them into the hydrant, I love the janky things that can happen when the hydrant pushes you, and I love the risk Pac has to take to grab someone. Pac is so friggin cool!