Dugtrio's meant to trap Pokemon with it's ability (Arena Trap), and kill them off before they cause more havoc to the team. That and it makes an excellent revenge killer with 120 base speed, a usable priority move, and a STAB EQ. Although it sounds good, it's hitting off a measly base 80 attack, which means unless it's Magnezone you're going to have to dent most Pokemon before it grabs a KO. And even then, it has pretty bad defensive stats and will get KO'd after your revenge kill.
Overall, I wouldn't recommend it at all for your team. It'll be fun to have around just to get random Pokes, but I have a hard time seeing it be useful as a whole.