Bombshell Crab
Source: Pet Battle. The natural habitat of these crabs is so polluted and devoid of shells that they've been forced to take shelter in discarded goblin munitions. Are ... Aquatic type. If you're having trouble capturing this wild pet due to its self-destructing ability, "Explode," I recommend clicking the white flag button to surrender and forfeit the battle.
The Bombshell Crab is a wild pet from The War Within expansion, captured by engaging it in pet battle combat in the wild.
Guide awaiting review
Handle the Explode Ability
If the Bombshell Crab has the Explode ability, click the white flag button to surrender and forfeit the battle without dealing any damage, which returns it to the map so you can re-engage it with a chance of it spawning without that ability. After roughly three surrenders, it typically appears without Explode.
Find It as Backline Pet
The Bombshell Crab can appear as a backline pet in battles initiated against other creatures such as a Varmint MK II or a Cave Crab. You can still forfeit and re-initiate the battle to reset its abilities as long as you have not killed the main pet.
Fight It as Backline Pet
If it appears as a backline pet with Explode active, use abilities that deal damage to all three enemy pets while healing your own, so that by the time it enters the fight it is already low enough health to capture. A pet with AOE damage and heals such as those provided by Inspiring Song and Sunlight can work well, with single-target damage used when those are on cooldown.
Hunt for the Purple Version
To obtain the purple quality version, find a Bombshell Crab as a backline pet, then engage and forfeit repeatedly to reset its color until a purple version appears. Use a healing-focused team to recover from forfeit damage, and deal AOE damage before capturing so it is already weakened when you attempt the cage.
Tips
Other players can kill the Bombshell Crab while you are in or have just left a battle with it, so act quickly once you locate one.