i started to play in a pathfinder group and i realised that they plan to play very optimized characters. Unfortunately im quite new to pathfinder so i have still problems to think of an strong eidolon...
So my question is about the Bite-Evolution:
If i upgrade the Bite-attack to 1,5 Str-Mod, does this also apply if i attack with a manufactured weapon in the same round?
You still have to follow the Universal Monster Rules for natural attacks:
Creatures with natural attacks and attacks made with weapons can use both as part of a full attack action (although often a creature must forgo one natural attack for each weapon clutched in that limb, be it a claw, tentacle, or slam). Such creatures attack with their weapons normally but treat all of their available natural attacks as secondary attacks during that attack, regardless of the attack’s original type.
Secondary attacks are made using the creature’s base attack bonus –5 and add only 1/2 the creature’s Strength bonus on damage rolls.
As soon as you add a manufactured weapon attack to your routine, it makes all the natural attacks much worse. Generally you either do one or the other.
Yes, the Str is only 1.0 if you have more than 1 Natural Attack.
An eidolon can take the bite evolution a second time to have a x1.5 STR bite when used with other natural weapons.
If the eidolon already has a bite attack, this evolution allows it to deal 1-1/2 times its Strength modifier on damage rolls made with its bite.
The evolution assumes this is made as a primary attack, but makes no explicit statement.
Personally, I would rule it as only dealing x.5 when used as a secondary attack, following the general rules for secondary attacks.