Dave first tried to take over by launching an assault upon the Stone Tower Zone, armed with a pair of guns and some rockets. He was quickly and easily taken down by Tekno the Canary, who disabled his already shoddy armour's defenses, and Sonic the Hedgehog, who dealt the final blow, before leading Tekno off to deal with ten more of Dave's ilk.
A few years later, Dave returned to the Stone Tower Zone, with new guns and a new suit of armour on rental, which still wasn't the best quality. Tails and Amy Rose arrived to put a stop to him, and to Dave's credit, he managed to get a couple of hits in this time, mainly because Tails got too close, and Amy was distracted by thoughts of Sonic's apparent betrayal of both the Freedom Fighters and Mobius. Tails began to gain the upper hand against Dave, and inspired by the fox's words, Amy rejoined the battle, damaging Dave's armour with a few well-aimed arrows, and brought him down with a kick to the chest.
It can be assumed that Dave is currently in prison, though this is debatable.