Trials Rising

If you're like me and already beat all these with the faster bikes, fear not. There's still a way to get this without facing the fastest riders.

Simply unplug your internet cable or disable your wireless connection for a few minutes, you'll also need to set the xbox you want to get this achievement on as your home xbox, then launch the game not connected to the internet.

Then simply select one of the monster mash supercross races and get 1st place. Easiest one is up to you but I prefer to race only one person instead of 7. Once you get 1st place the achievement won't pop until you plug in or enable your internet connection again.

Hope this helps anyone as mad as I was for a few minutes there.

Not as difficult as it sounds. Once you unlock the Monster Mash stadium event, you need to come in 1st place using the squid. I’m pretty sure you have to win even though the achievement doesn’t specify it. I qualified on the first event, came in 2nd place and it didn’t pop. Came in 1st place on the second event and it popped right away.
Make sure to keep your jumps low so you can spend as much time as you can with your wheels on the floor getting that needed acceleration. Keep practicing the track and retrying until you get that 1st place!

*As BryanLovesCowzz has kindly pointed out in the comments, if you have already completed these events, you will come up against much faster racers. This may or may not be a problem for you, but if it is, the other solution by Chicago AJ explains how to get round this. Basically it just means taking your Xbox offline so it can’t bring in times from online and then completing the event offline.*

Beat any of the monster mash races using the squid

First i tried the first one where you have to come in 4th place but sadly i came in last and it was a bad race. So i tried the second track where you have to come in 2nd and on my first go at it i came in 1st.

When you click on monster mash once you have that event unlocked, select the middle one that has the number 4 on it then select the squid. Seems lot easier with 4 A.I. instead of 8.

Try not to go full throttle when your racing cause you won't get anywhere. You might if you get lucky. If need too, practice on that track while trying to go for this achievement. It's not as hard as it may sound.
When going up the ramp and onto the next ramp going down try not to hold the gas for too long while going up the ramp cause it will make your bike go far up in the air. Just apply enough gas so your bike can go a bit faster onto the other ramp. Using the brakes could also help to make your bike go faster.

Not sure if you actually have to come in 1st place or not but apparently according to the other guide above me It didn't pop for him when he came in 2nd place.

Hope this helps.

Happy hunting.