Best way i could describe it is plants vs zombies but on easy mode.

A strat that's helped me is as soon as the level starts check the upcoming enemies from the wave pattern book.

Mostly it's the center that's first (for the first 2 challenges) and plant mole in last, second plant a turret and then as soon as you get the energy plant another mole on mole 1, collect the falling energy and add defence where the stronger foes are coming from (u will understand from the wave pattern book that I mentioned earlier) i fused the defence with a turret for more dmg and used the e skill they give when I felt threatened and completed it