ZHEROS

I tried the other solutions and levels mentioned but it didn't work for me since i was mashing up enemies too fast or my combo was interrupted. The one lvl that worked for me was 1-7 (walkway) on normal difficulty with melee upgraded to lvl 2 if that matters. Once you passed the 3 fire obstacles and get to the inside area/ hangar there are 2 vehicles/robots available. Grab one (preferably the one on left down side) and head over to the down right where 3 fangs will spawn - at least thats where i started. Key is to just hit X once then stop for about a sec, head over to the next group of enemies and do the next hit. Advantage is that you can't get knocked back or stunned while in the robot so you have a bit more control and can keep the combo going easier. After an enemy is killed another one will spawn and there is plenty of enemies in this area. So take your time to let enemies spawn - find your rhythm. If you don't get it on your first try leave the vehicle and walk further on to the electrified floor to your right after the next door and get yourself killed. You will spawn a bit before entering the hangar. You simply need to kill some bots and a fang, pass the three fire obstacles and the fun can start again. If you can improve this method or got any questions let me know.

Here's a video of me getting the achievement on level 1-6 (Sector Zero - Factory). On the 4th stop, there will be about 15 enemies that spawn. Just keep hitting XXX and moving on to the next group. The achievement unlocks at around 66 hits, but I show that it is possible to get 114 hit combo in this spot just in case the achievement is patched to be same as the description.


Edit:
Thanks x Mataeus x for the info:
***PATCHED***
You do now need a combo of 100. I can confirm this after getting a 91 hit combo ("Punishing") and having not unlocked it, with the achievement counter at 91%. Gutted!

OK For me I got this on easy once I got my moves list up to level 3.

I used the "gunner" move on a whole group of enemies at the beginning of level 1-8 .

You can get a combo of around 20 on one enemy using this and if you find a group, you can get this really quick. Hope this helps as I struggled with all the other methods.

This is for getting a 100 combat streak, but I don't even think i needed 100, it looked like it popped after about 60 or 70?

Anyway, I got this In stage 1-4: there's a section a few minutes into the level (after the robot dog fight), where you walk north into a big green room with see-through grating as the floor, and has a big red button you need to hit. A whole bunch of enemies will spawn, in which you can keep your combo alive for a while. Just keep mashing X to attack, but also try to mix a few styles of fighting in. For example, when playing as the tough guy character you can use the roll forward/attack combo - this throws enemies into the air and does more attacks at a weaker strength.

Building on Psparky27's solution, use level 1-8 and wait until you go up in the elevator. Take out the shield guy and then use the combo and concentrate on the bombers because they can take a bit more damage before you hit them up in the air. Here's a clip I recorded of using this method to get a x125 combo.

Since both of the other solutions suggest using level 1-4, I thought I'd give an alternative that worked better for me. First off, I suggest playing on normal or hard and using Mike with 2 upgrades into his melee abilities so you have the 5-hit combo move that only uses . Load up level 1-6, which starts off as an elevator level. Once you reach the fourth stop, which is the stop after you have to fight the giant space cow mini-boss, a bunch of enemies will fall from the sky, and even more will spawn periodically. Simply press repeatedly and move from enemy to enemy. They tend to group up in the small space, so it's pretty easy to keep the combo moving up. Just make sure to map out which enemies will be next so you don't start punching empty air and lose your streak. The achievement will unlock once you break into the 60's (as of Feb. 5, 2016)