I cleaned up Roo's movelist formatting so it can be included here and people can learn to appreciate mister kangaroo!
Oh, and SoR2 Axel's Tatsumaki Kick is listed as his Forward + A offensive special when that's his Dragon Smash; the Tatsumaki Kick should probably be listed separately as Forward Forward + A. Also, Axel's defensive special is Dragon Wing; the rapid multihit punch offensive special is what's called Dragon Smash.
Rush Combo - B, B, B, B (Jab, jab, double punch, backflip. Poor range, backflip won't knockdown if you're too far)
Back Attack - B + C (Tail whip, no knockdown at long range so it can be spammed to keep enemies staggered. No longer hits in front like in SoR3)
Defensive Special - A (Tail Flip, multihit attack that's weak if you hit enemies while they're jumping)
Offensive Special - Forward + A (Tornado Kick, no longer invulnerable when using it like in SoR3, slow enough that enemies can punch you out of it)
Vertical Jump Attack - C then B, without moving left or right. (Quickly whips his tail straight forward, difficult to hit with)
Jump Attack - Forward + C then B (Jump kick with good range, but is a bit weak. Roo also doesn't keep his legs extended throughout the jump kick, so it's less safe to use than other jump attacks are)
Diving Attack - C, then Down + B (Roo pounces on enemy with both feet)
0 Star Blitz - Forward, Forward, B (Nose Slide. It's possible to slide right through enemies without knocking them down if you use it too close to the enemy.)
1 Star Blitz - X, Forward, Forward (Upgraded Nose Slide, moves much faster.)
2 Star Blitz - X, Forward, Up (Roo slides forward and does a spinning jump attack with his tail)
3 Star Blitz - X, Back, Forward, Up. (Roo does a spinning tailsweep followed by a jumping attack)
When grabbing an enemy from the front:
Forward + B (Kicks the enemy, can do this up to three times, 3rd will knockdown)
Neutral B (Headbutts and immediately knocks down the enemy)
Back + B (Throws the enemy behind Roo, his best grab attack)
When grabbing an enemy from behind - B (Roo repeatedly kicks the enemy followed by knockdown, very weak for a rear grab attack, invulnerable to almost everything while using it)
Team Attack - While grabbing your teammate from either side, press C, or let yourself be thrown by teammate (unique jump attack with both feet first).
If grabbed from behind (by either enemy or teammate) - C kicks forward, during the kick press B to counterthrow the enemy. (No longer counts as a slamming throw like it did for Roo in SoR3. If you're grabbed by your partner, using the counterthrow will instead throw your partner into their team attack)
While holding any weapon, throw using B + C or the Back Attack button.
Roo can't use guns. Instead, any time you try to pick up a gun he immediately throws it in the direction he's facing. He can use grenades and pepper spray just like any other character.
While holding a knife/kunai/bottle:
B (Quickly pokes forward with the weapon)
Forward, Forward, B (Does a jumping upwards slash with the knife, like Blaze's running knife attack. Not usable when holding a kunai or bottle)
Forward + A (Spinning slash with knife, not usable when holding a kunai or bottle)
While holding a baseball bat/metal pipe/wooden plank/sword:
B (Roo swings the weapon over his head and brings it down at an angle)
Forward, Forward, B (Roo performs a spinning slash, only usable with a sword)