Okay, so...
While Tails is capable of using the Spin Dash. He lacks spikes, so any attack that Sonic performs in Smash that uses spikes (example: the aforementioned up-throw) is off the table.
In almost all of Tails' appearances, he is shown flying using his tails, in the games with Co-Op modes (Sonic 3, Sonic 4.2, Sonic Heroes, Sonic Advance 3), he is shown to be able to carry people (usually Sonic) while flying.
In Sonic Battle, Tails can use a robotic boxing glove on an extending arm to attack (it's weird, I know), while also having a small "Chu-Bomb", based on the Chu-Chu Rocket games.
In Sonic Heroes, he has an attack called Thunder Shoot, which allows him to 'fire' carried allies at enemies. In Sonic '06, he uses an item called the "Dummy Ring Bomb", which is exactly what it sounds like, he throws fake rings that explode.
There's also Tails Adventure for the Sega Game Gear (one of Tails' earliest appearances), he has actual (cartoon) bombs, along with a small robot helper that has a few uses of it's own that I can't immediately recall right now. I believe he also has a Drill in that game, too?
Finally, in Sonic Adventure, not only can Tails fly like usual, but he can also use his tails to attack by spinning, he also does this in the Sonic Advance trilogy.
I believe this is a comprehensive list of everything Tails can do off the top of my head.
I'd also cover Shadow's capabilities, but he wasn't asked about.
