Naughty Bear

The first mission in the episode 8 free DLC will become your best friend whilst you grind out this achievement.

Play as Master Miyagi so that the Superbears/Normal bears don't attack each other and waste those valuable points and stick to the usual rules you'll be well rehearsed in by this stage in the game.

- Keep them alive as long as possible and make them insane
- Only ever kill them with (varied) super kills if needs be
- Save Unibear statues until you have a 100x multiplier

I was averaging 7.5 million per run through of this level, once hitting over 8 million and landing second place on the global leaderboards. It's time consuming, but doable with some patience.

Alright,to score this many points I recommend you starting episodes over,trying to get more naughty points. Some ways to get this much are:
1.killing with a large variety of guns,sabotages,etc.
2.let bears escape because after they do 2 other bears will come.
3.destroying alot of items.
4.doing naughty things in front of other bears
5.locating all of the naughty time capsules and get them when your multiplier hits 100.
6.doing number 4 to make bears insane so when they run around,other bears will be scared!

hope this helps!

The easiest way to get this without the DLC is replay Episode 5 or 5-3 Killer. I was averaging 6 to 6.5 million per run. Choose the Unibear costume as he is insanely fast. Use traps as much as possible. Try get all the B.E.A.Rs to bunch up, as doing something like killing in front of all of them will net you tons of points. Make sure to destroy the badges quickly with the 100X or 75X multiplier. For 5-3 Killer, make sure to destroy the car & boat of each section at the very start, as if they escape, you lose.

The DLC episodes also count towards this.

Once you've beaten the main game. and if your total is not 250 million, just continue to play the DLC.

It's better than being bored out of your mind replaying main game episodes, and i'm sure you'll be going for the DLC achievements anyways...