We use Kepler K2 Campaign 4 short-cadence ( one-minute ) photometry to measure white light flares in the young , moving group brown dwarfs 2MASS J03350208+2342356 ( 2M0335+23 ) and 2MASS J03552337+1133437 ( 2M0355+11 ) , and report on long-cadence ( thirty-minute ) photometry of a superflare in the Pleiades M8 brown dwarf CFHT-PL-17 . The rotation period ( 5.24 hr ) and projected rotational velocity ( 45 km s ^ { -1 } ) confirm 2M0335+23 is inflated ( R \geq 0.20 R _ { \odot } ) as predicted for a 0.06 M _ { \odot } , 26-Myr old brown dwarf \beta Pic moving group member . We detect 22 white light flares on 2M0335+23 . The flare frequency distribution follows a power-law distribution with slope - \alpha = -1.8 \pm 0.2 over the range 10 ^ { 31 } to 10 ^ { 33 } erg . This slope is similar to that observed in the Sun and warmer flare stars , and is consistent with lower energy flares in previous work on M6-M8 very-low-mass stars ; taken the two datasets together , the flare frequency distribution for ultracool dwarfs is a power law over 4.3 orders of magnitude . The superflare ( 2.6 \times 10 ^ { 34 } erg ) on CFHT-PL-17 shows higher energy flares are possible . We detect no flares down to a limit of 2 \times 10 ^ { 30 } erg in the nearby L 5 \gamma AB Dor Moving Group brown dwarf 2M0355+11 , consistent with the view that fast magnetic reconnection is suppressed in cool atmospheres . We discuss two multi-peaked flares observed in 2M0335+23 , and argue that these complex flares can be understood as sympathetic flares , in which a fast-mode MHD waves similar to EUV waves in the Sun trigger magnetic reconnection in different active regions .