Thank you very much!!

I suggest first creating a fill clock. If you don't know what that is, place a command block on the ground with this command (fill ~ ~1 ~5 ~ ~1 ~ minecraft:bedrock) or something similar. Then, two blocks above that command block, place another command block with this command (fill ~ ~-1 ~5 ~ ~-1 ~ minecraft:redstone_block) or something similar. Then, place a command block in between the two. You notice that unbreakable redstone blocks span out about 6 blocks.
After creating this fill clock, hook however many ./testfor command blocks up to the redstone blocks (example: testfor x y z minecraft:mob_spawner). Connect comparators to the ends of these command blocks. Make these comparators run into blocks; every comparator should have a block that it feeds into. Place redstone torches on these blocks. Then, place two blocks in front of all of the blocks that the comparators feed into. On the second row (the one next to the redstone torches) place redstone dust. Connect this redstone dust up to repeaters, and these repeaters feed into a new line of blocks. Place a redstone torch on top of this new row, and then on these redstone torches place the command blocks you want to activate after all of the testfors are true.

Example:

Here, I'm testing for a Cow and a Chicken in the caged in area above. If both are true, the comparators will turn on, which turn off the torches, which turns off the redstone, which turns off the repeaters, which turns ON the torches enxt to the command blocks at the far left.

This was a good hour of work. Hope I helped!

/testforblock