Bloontonium Lab is one of the hardest tracks in BTD5, and is one of the couple Extreme tracks. Its three completely separate short paths that only come close together in the middle makes this extremely difficult to beat, especially on hard. If you don't get up a good defense quickly. M.O.A.B. class bloons will give you massive problems.
It's recommended to at least use the 3-tier Dart Monkey Specialty Building if you're trying to beat the map on Hard. Even though it's not impossible to beat the map on hard NAPS, it'll most likely take you a frustrating amount of attempts and a bunch of monkey money to come up with a NAPS strategy.
Note that the strategies written below won't guarantee a absolutely win, especially on hard difficulty. These are merely guidelines to help you have a general understanding of what you need to do to beat the map.
It is important to note that the bottom path is shorter than the other two due to the aspect ratio of the screen.
Starting with 6 dart monkeys happens to be a great idea, along with building up many Banana Farms, utilizing the unupgraded Spike Factory to take care of loose bloons and using Corrosive Glue (Upgraded to 2-2) and Lightning Monkey Apprentices to deal with the leads and the rainbows. A Super Monkey should be placed as soon as you have a stable cash flow from your 5-6 Banana Plantations mid-way into the game. Try to build an Arctic Wind Ice Tower in the centre by Round 40+. But to ensure they can detect Camo bloons, a Radar Scanner is also necessary. Higher levels (70+) should generally mean that you should start buying more Sun Gods or Robo-Monkeys. Note that the strategies used for other tracks probably won't work here.
(Monkey tycoon and double cash advisable.) buy many dart monkeys then sell to get a super monkey with super and epic range, then get a radar scanner ASAP. Buy and sell bionic boomers for lead levels 1 and 2 (not needed on easy) then get robo monkey. DO NOT GET LASER/PLASMA YET!!! Get monkey town/high energy beacon and arctic wind. Get more robo monkeys, then progress on to sun gods. Get 1+ temple of the monkey god. Spike factories for glitch regrowers. Kill ZOMG. Win.
What may work is a strong tower (Bomb Tower, Monkey Apprentice, Ninja Monkey) in the middle, with many speed and range upgrades, and then Glue Gunners and Ice Towers (You know, towers that slow and stop bloons) around it. Unfortunately, Spike factories will be very hard to work with here, as they are expensive, and where you really need them is at the end. But, you canot place a Spike factory so it can send tacks to the ends of more than one path. You can place one so it can send tacks to the beginning-middle, or middle-end of two, or even the middle of three, but there are very good reasons why those probably will not work, most of the time. First, putting a Spike factory in the center of the track takes up valuable space, and you'll probably just have to sell it when you start working with Super Monkeys. With a Bomb Tower or a Monkey Apprentice, however, you can place them very close to the exact center, and then they can be sacrificed and used for a Temple of the Monkey God, if you make it far enough to be able to afford, place, buy, and use one. Get Super Monkeys as soon as possible. And a trio or quartet of Dart Monkeys inside of each track isn't a bad idea. But remember-make sure you have your strategy completely mapped out before you start, otherwise you could waste lots of Monkey Money.
Strategy 4 (Sam Wang)Edit
Start with 3 dart monkeys. After that, buy 3 more dart monkeys with targeting set to strong in the edge of the middle circle. This is because you will need to save up for a 3/1 bomb tower in the center and target set to strong later. Upgrade the bomb tower to 3/2 and even 4/2 if needed. In the meantime, start buying and upgrading banana farms on the first path until it is upgraded to a BRF, then upgrade it to 4/2. Also, don't forget to put super monkeys (3/2 and 2/3) along with adding more powerful towers. An artic wind is recommended to be placed in the center.
You need 3 Pro Tribal Turtles and a Portable Lake.
Place your agents in the middle.Place a Triple Darts too.You also need Dart Training Facility Tier 3.Get a Monkey Buccaner.Upgrade it to Destroyer as soon as possible.Get a Super Monkey with a village as soon as possible.Upgrade Super Monkey to Laser Blasts in a few rounds if possible.Upgrade Village to Rader Scanner to make Super Monkey target camo bloons.Upgrade Super Monkey to Plasma Blasts and then Robo-Monkey.Try to get another Plasma Robo-Monkey before first M.O.A.B comes.Win!
A Premium Upgrade is useful and is highly advised if you have enough Monkey Money, and can let you win on Medium.
Strategy 6 (Mobile)Edit
Requires 1 Radactyl, 3 Pro Bloonberry bushes, 1 Portable lake, 1 banana farmer, and 7 Pro super monkey storms. Monkey Money needed 630.
Place Radactyl in the center and place your 3 Pro Bloonberry bushes on the 3 ends of the track, You will also need 3 Dart monkeys on the yellow lines next to the center. Get a (3,2) Bomb Tower and place it above the Radactyl. Get 4 Banana Farms in the bottom right and place a Banana Farmer near them Get a (4,2) Bloonchipper and place it on the right side of your Bomb Tower. now Upgrade Bomb Tower to (4,2). upgrade all Banana Farms to (1,1). (Optional) Get a Mortar Tower (0,2) and aim it on where your Banana Farmer Leaves the peels (Pro Banana Farmer) so nothing can duplicate. Get a (0,2) Village and place it on the black lines near your Bomb Tower and Bloonchipper. Now get another (4,2) Bloonchipper and place it on the left of the Bomb Tower. Get another (0,2) Village and place it near the other Bloonchipper and Bomb Tower. get a 3,2 Ice Tower and place it under the Radactyl ( should be done before round 63. Get a 3,2 Super Monkey. As you saw you might have needed Road Spikes. Get Lots-O-Bloonchippers (4,2). Use 1-2 Pro Super monkey storms on round 77 if needed. Upgrade Ice Tower (4,2) before round 76. On round 84 sell a Banana Farms, Villages, Bomb Tower, Ice Tower, and about 1-3 Bloonchippers. get 3 monkey aces (2,4) use there abilities. Great now sell All Guys including all agents placed, now place Portable lake Get Sub (2,4) and use Ability Win! Warning might need some pro Super Monkey Storms on round 84. I Won With this.
Strategy 7 (Mobile Only)Edit
1. Start with cash injection. But don't need to if don't want to
2. Buy Farms 4/2 and get a lot of Monkey Engineers. Upgrade them to 4/0
3. Get a HEB in the center. Also get Bloon Impact for the ceramics.
4. Sell all towers to get TOMG w/sacrifices. Switch to it's specialty building, then use Dark secret ability to destroy the 5 Z.O.M.G.'s
Use SMS if needed. I used only 2. Farms and bloon traps really help on impopable. Helped me pass all the tracks on impoppable.