> Here's a handy heuristic: if somebody claims to know every x86-64 instruction (or even every x86-32 instruction), you can be at least 90% sure they're lying.

I very much prefer ARM myself, but you can probably apply the same rule of thumb to it. There are upwards of 400 instructions both in AArch32 and AArch64, with a fair number of differences between the two.

Edit: I've also posted a breakdown of the immediate limitations for ARM in this thread. It's not that complicated when sticking to the standard instructions.