for example, Gear looks alot like Haguromon from Digimon
Well, yes, they're both... y'know, based on gears? If two different franchises base a critter on the same inanimate object, guess what? The critters are going to look similar. Let's say that by some cosmic twist of fate Gear preceded Hagurumon chronologically; the argument would be reversed and yet the answer would still be the same. When that's the case, the argument was flawed to begin with.
and Munna looks a little like Tokomon
This is a stretch. They share a vague body shape and being quadrupedal. Nothing else. Tokomon is off-white, has giant teeth, cheek marks and antennae thingies. Munna is pink and purple, has no visible teeth and instead has an extended nose that vaguely resembles a short trunk and has no other visible protrusions.
By this logic, every creature, fictional and otherwise, to be small, quadrupedal and colored a soft hue looks like one another.
but I honestly think that pokemon is running out of ideas and that is why they look different.
Were we to sit here and list all the animals and reasonable inanimate objects that they either have yet to use as the basis for a Pokémon or are broad enough to serve as the basis for multiple designs, we'd get about 10% of the way through that immensely elongated list and determine "ok, fine, there's still hundreds of thousands of things they can use as the basis for Pokémon."
They are most certainly not running out of ideas.