1. Make them defend some squishy targets and pay them based on how they survive
2. Explosives, stun grenades and area effects. Explosives are often the best way to take nearly anything down, but it's also treading on dangerous TPK and angry player territory. The other thing is that corps often don't want to blow their own place and stuff up. Stun grenades and smoke grenades are better. Just having guards toss around stun grenades and duck behind desks is hideously effective. Actually, it can also lead to a TPK, as I was a player in one recently. (Although it was Company Men tossing the grenades, not rentacops, so that also made it works so well, perhaps too well, because even if the throw fails, a building is an enclosed area and there's still a decent chance of PCs being stunned. And even if the guards stun themselves, the players were going to kill them anyway. And there can be more guards. Kind of a cheap tactic, but not too bad if used by rentacops.
3. Just some smoke grenades, rentacops, and some doors not connected to the Matrix can cause a team to fail a shadowrun due to time constraints and the police coming.
4. Open ground and guards with sniper rifles or hunting rifles. Towers for them if you want it worse. And if you really want to be a jerk, make it an MTC Zero Zone with killer drones, gun enmplacements, and clouds of nerve gas.
5. If your players are walking around in military spec armor, take it away. There are missions where it's possible to wear it, but they shoudn't be the norm. Make use of checkpoints. My street sam is nearly always forced to use Ingram Smartguns, precisely because they are concealable.
6. Pincer movements. This is usually done by SWAT and response teams. They come at the runners from more than one direction. Make use of skirmishers too, just like you'd do in a strategy war game. Some light forces whose job isn't to win, but to just distract or pin down the runners, while the experts flank them. The skirmishers may make use of grenades or smoke grenades.
7. Design the battlefield to favor the defending corp forces. Give them cover and take the runner's away.
8. Ninja archers, especially strong ones.
9. Spirits. These make great skirmisher forces, as mentioned above.
10. Ares Screech and sonic weapons.
11. Vehicle combat. My players are frightened of this because crashes are so deadly.
.So they've got their heads on straight, and their rep is pretty solid. Definitely paracritters. Or a run in with a forest of man-eating trees.
Ah yes, packs of hellhounds.