Let me divide the rounds into 3 categories: easy, average and hard.
Easy rounds are: Peasants, Bandits, and Weaboos.
Average rounds are: Nomads, Sea Raiders and Rohirrims
Hard rounds are all the rest, so: Vitezi, Engineers, Sexies and Tincans.
Easy rounds don't require much of a tactic to beat them. Brutal strength prevails!
Average rounds require a little brain power, for example using rooftops for getting enemies stuck, huts for easy slashing, and fences.
Now, hard rounds require a bit of thinking, tactics AND improvisation, as bots tend to NOT follow the players plan. Especially applies to Engineers and their crossbow batallions.
Most typical tactics are:
Charging
Hardly a tactic, its most commonly used on Peasants, Bandits and Weaboos. Players challenge bots with their own brutal power, which often causes losses, but profits in time.
Fence Stuck
Most often used (given there is a fence on map), its also most effective tactic for non-ranged bots. Few players stay inside the fence, bots concentrate on trying to get on them, and as a result get stuck, allowing other players to easily attack them from behind. Important part is for either ALL players to stay inside fence, or few stay AWAY, so bots don't get lured away and cause chaos.
Hut Stuck
More rare sub-tactic of fence stuck, has 2 versions:
a) Jump-in hut - Hut that requiers a jump to get inside, 2 to 3 players-slashers inside, bots trying to get to them and getting stuck at the entrace, becoming an easy prey for slashers inside.
b) Ground-level hut - Normal hut thats possible for bots to walk in, takes one shielder (at least one, spare shielders welcome if the primary one dies) and 2 slashers on sides, finishing bots that try to kill the shielder. A bit more risky, as sometimes bots can squeeze in-between the players and start hurting them, but still very effective.
Uber-shielder Stuck
Person with dedicated shielder only build (around 12-13 shieldskill) lures bots into a corner, and blocks them with their indestructable shield, while players finish enemy from behind. A risky tactic, as dedicated shielding causes player to be very weak (3 str) and often die on 1-2 hits or headshot (even with a stone)
Rooftop Stuck
Often used as last-chance tactic, few players stay on the rooftop (usually ranged ones), and rest hopes that bots are dumb enough to get stuck trying to get to them and can be finished off from behind OR by ranged themselves. Sometimes result is hillarious when bots manage to climb up to the roof and massacre the surprised archers and crossbowmen.
"The Train"
My personal favourite, a silly tactic for people too dumb to teamwork :D (like me), requiers a hill and a long enough weapon. Player lures bots to himself, sometimes entire wave, and starts walking up the hill, facing bots and slashing them whenever they come close. Takes great timing skill to keep enemies away, but its often uneffective on later rounds that have ranged bots able of shooting down people brave enough to do The Train. (Additional swag points for saying "Tchuu tchuu" during the attempt of Train)
Seriously thou, its quite an effective tactic, but often time-consuming.
Ye olde shieldwall
Once a trademark of teamwork and cooperation in DTVillage, now mostly a forgotten tactic, Shieldwall involves shielders making their stand in tight passages, where they halt bots, making them vulnerable for other players. On a more serious note, its still sometimes used, but loses its sense after Sea Raiders, whose axes make a short job of SHIELD in shieldwall.