As any character, win a match with the Bomber field event active without ever getting damaged by a bomb.
It is recommended to play on larger stages with branching paths like Sealed Archive, White Winter, or Starship, so as to give bombs as wide a berth as possible. Since detonation of individual bombs varies, it involves a bit of luck, but generally including Sprint as another field effect and several Dash!'s in your deck decreases that risk a bit. Also choosing a character with a very mobile hyper like Suguri, Sora, or Mixed Poppo helps. Undesirable field effects would be Backtrack, Confusion, and Random Warp.