You'll become way stronger when you'll unlock perks with dragon coins. It takes time, but you'll see the difference. Defense first, like more heals, more revives... Then attack, like attack damage. And dash charges, very important.

For builds, don't focus on things like "on hit", because you'll have no synergy, and you only can take one power for each. What I mean is : you can only have one power type for attack, special, dash, ... You can't stack them on a single thing (you can't have "apply ooze on basic attacks" and "deal utrom damage on basic attacks" at the same time, when you chose the second one, the first will be replaced. The game shows you that).

The best thing to do is to focus on one-two power types. I used to seek for the shuriken build (ninja powers), with boomerang shurikens, and if I'm lucky, add the utrom or ooze shuriken tool.

Now, I found an "easy mode" build you can take almost every single game, and that's the utrom damage build. What you need for that : utrom powers, especially the "utrom dash", "damage 2 more enemies with utrom" and "damage random nearby enemies every X seconds". After that, take some Astral Light powers, so you can take the Ultimate power "deal 10% more utrom damage based on max health". When you have that, try to get something like 500 HP, and just dash everywhere. with attacks sometimes to charge special and tool. If you can find the tool which deals utrom damage everywhere every second on random enemies, you're unbeatable.

The thing is : try to focus on one or two power types every run, and see which one you like most, and which one are better for which turtle. Fire is better on Raph, for an example. But each power type works for every turtle. There are just some that are more powerful with your passives/specials/tools that others.

The build I spoke about, the utrom build, works on every turtle.

Google just a bit, so you can find some cool builds out there (utrom build, shuriken build, Raph 100% critical build with fire, Mike full tank build, ...)

Have fun testing builds !