This is the final Trial level, "Teach me Lights, Teleport and Cloner". You have three lemmings and need to save two. 10 minutes is more than enough time.
As your lemmings walk to the right, they'll light up candles, making it easier to see. Make the last lemming into a Blocker.
Right after a lemming passes the second candle, make it into a Builder. It'll build steps into the third column.
Go ahead and make this lemming a Climber as well. The third lemming will continue forward, falling off the edge of the map. Don't worry, he isn't needed. When your Builder is finished with his steps, he'll turn around, run into your Blocker, and then come back up the steps and climb the pillar.
At the top of the pillar is a teleportation device. Your lemming will walk into this.
Your lemming will exit out of another teleportation device, the same color as the one it entered. As your lemming walks forward, he will pick up an extra Builder ability.
Right before you reach the green teleporter, change your lemming into a Builder. If you enter the green teleporter, you'll end up at a trap.
Your lemming should continue forward, walking into the blue teleporter.
The lemming will exit the blue teleporter here.
Your lemming will climb up the left grating and then continue to the right.
This device is a cloning machine. It will clone the first lemming that walks by it. The clone will also have all the abilities of the original lemming.
Now you have two lemmings to save. They will exit the level together.
If the level doesn't end on it's own you can press the select button to bring up the game menu.
Choose Finish from the game menu to end the level.
You have successfully completed the Trial levels! Press X to continue. You'll be taken back to the last Trial level's preview screen. Choose the O button to go back to the previous menu, where you originally picked "Trial" out of the difficulty choices.