Assume a 12th level unchained summoner.
And yes, it would likely be easier with the original summoner, but it's not available to me.
Start with 4-legged aberration:
Pair of Legs [Free]
Pair of Legs [Free]
Bite [Free]
Grab [2] -> attaches to bite
Tail [3]
Tail slap [4]
Large [8]
Tentacle Mass [9]
Gives you 3 attacks, represents it's back, tail, bite, and it's weird tongue.
If you wanted it for power level, drop tentacle mass for claws to get to 4 attacks:
Pair of Legs [Free]
Pair of Legs [Free]
Bite [Free]
Grab [2] -> attaches to bite
Tail [3]
Tail Slap [4]
Large [8]
Claws (legs) [9]
That said, it spinning around kicking a bunch is much less cool I imagine, given that you have this crazy creature in mind. I would give it at least Cleave if you take the tail, that way you can swipe multiple opponents at once.
If you don't need it to be large it becomes trivial to get it to 5 attacks, and you may look towards some defenses. I figure Grab + Large not only gives you synergy, but it gives you a lot more damage per attack, and some health to hide behind.
that's really acurate, actually. nicely done!
Thanks Cattleman, that's a wonderful guideline!