Start a Versus mode game. In the match options, uncheck "Ball Tagging" so that the ball is not tagged upon being hit. Then, just get hit by your own ball.
<br><table width='100%' cellpadding=3 cellspacing=3 border=0><tr valign='top'><th>Achievement</th><th>How to unlock
</th></tr><tr valign='top'><td>1st Division</td><td>Play one thousand matches.
</td></tr><tr valign='top'><td>2nd Division</td><td>Play five hundred matches.
</td></tr><tr valign='top'><td>3rd Division</td><td>Play a hundred matches.
</td></tr><tr valign='top'><td>Ace Player</td><td>Reach level 20.
</td></tr><tr valign='top'><td>Bats In The Dark</td><td>Reach a ball speed of two hundred fifty.
</td></tr><tr valign='top'><td>Boomhammer Beatdown</td><td>Beat the challenge mode with Sonata.
</td></tr><tr valign='top'><td>Chrono Warp</td><td>Reach a ball speed of one thousand.
</td></tr><tr valign='top'><td>Chrono Warp Cluster</td><td>Reach a ball speed of a hundred thousand.
</td></tr><tr valign='top'><td>Clutch</td><td>Bunt the ball at 1000 speed or above.
</td></tr><tr valign='top'><td>Doombox Slam Dunk</td><td>Beat the challenge mode without using any continues.
</td></tr><tr valign='top'><td>Double Play</td><td>Hit two players in a row.
</td></tr><tr valign='top'><td>Firmware Remix</td><td>Beat the challenge mode with Switch.
</td></tr><tr valign='top'><td>Full House</td><td>Beat the challenge mode with every character.
</td></tr><tr valign='top'><td>Grand Slam</td><td>Reach a ball speed of one million.
</td></tr><tr valign='top'><td>Lethal Rivals</td><td>Rally the ball back and forth for at least ten times.
</td></tr><tr valign='top'><td>Mass KO Production</td><td>Hit three players in a row.
</td></tr><tr valign='top'><td>Old School</td><td>Get hit by your own ball.
</td></tr><tr valign='top'><td>Rifle Strike</td><td>Reach a ball speed of one hundred.
</td></tr><tr valign='top'><td>Rookie Player</td><td>Reach level 10.
</td></tr><tr valign='top'><td>Sweet Victory</td><td>Beat challenge mode with Candyman.
</td></tr><tr valign='top'><td>Underground Revolution</td><td>Beat the challenge mode with Latch.
</td></tr><tr valign='top'><td>With A Twist</td><td>Beat the challenge mode with raptor.
</td></tr></table>