It's obvious you aren't capable of an intelligent debate, let me purge your thesis that "cat's are better than Mudkips" with a short little parental thesis of my own.
If you're buying cat over a Mudkip , you're not just ordering a fairly boring pet, you're actually degrading yourself - choosing a garden-variety creature, an unloyal and distinctly reality-disjointed creature at that, over a fantastical one at that is bad enough, being not ceasing to claim it's superiority when you have obviously had no experience whatsoever in conversing, training, or even relating with Mudkips, is an effort of pathetic proportions.
However, you can take it from the hands of an expert - Mudkips make the perfect pet. Training them can be a little harsh to begin with - as with most Pokemon their relationship with their masters is completely built on a dominance-subjective relationship, considering their complete willingness to obey you after defeating them in a battle. However, despite the obvious setback that you have to be stronger, or at least command something stronger then your chosen Mudkip to win it's loyalty (see: Pokemon dominance in battles) this also has it's advantages - unlike cat's, it's loyalty is absolute, and the Mudkip will follow you to the ends of the Earth and back if necessary.
Once their loyalty is won, the possibilities are practically endless - Mudkips make great house-guards, simply to the sheer power level they can be leveled up to - and despite common fear, the simple use of a Moon-stone can prevent evolution without any adverse side-effects - and since evolution has been proven to directly increase the effectiveness of certain Pokemon ( Metapod , for instance) this practice has actually been recommended by most top Pokemon professors for Pokemon-owners who wish to keep their Pokemon as housepets.
As you can see, the Mudkip is one of the cutest animals in the animal Kingdom, which also makes them doubly effective as a housepet - great to snuggle up with, they have great affection for their owners, like most Pokemon that are fairly treated.
As a bonus, you can even alter them, over the course of training, into the different forms - as the Soviet Mudkip which is shown here.
So, QED, Mudkips are the better pet.