Laws of mathematics are actually theorems derived from axioms according to a few simple rules of logic. The mathematics taught in school are mostly based on a few very common sets of axioms, but university-grade mathematicians are aware that different axioms lead to different theorems.
- A famous example is the difference between Euclidean and Non-Euclidean geometry.
- Another example would be arithmetic with the numbers on a clock. Two hours after 11 o'clock it is 1 o'clock, twelve hours after 11 o'clock it is 11 o'clock again.
These "different mathematics" all exist in our universe, insofar as one can talk about existence in this context. We select the right model for the purpose.
Most of your examples are not "laws" as mathematics understands them, which makes them difficult to assess.
- 2+2 = 3 means 1 = 0. If you want to do arithmetic, 0 is your only number.
- a/a = 3 means 1 = 3. That's a cyclic group.
- Pi is not an axiom.
- -5 > 5 means you simply switched the symbols > and <.