Can we stop wasting our time on pedantic details please? This conversation is irrelevant to the main EVO process, which needs to be decided before EVO will even happen. Unless of course people don't want to have EVO some time before the 5th gen comes out, in which case by all means, waste your time here.
Agreed.
Basic Guidelines:
An Evolution should have no more than 540 BST, unless it is some kind of Pseudo-Pseudo-legend (Togekiss, Arcanine), in which case it can have up to 555 BST or it is a Dragon/Dragonesque (Ttar, Dragonite, Garchomp, Salamence), in which case it can have up to 600 BST.
An Evolution should, in general, have a higher base stat in each individual stat, however, exceptions can be made in any stat except for HP (Vibrava has lower attack than Trapinch, Poryz has lower defenses than Pory2, Magnezone has lower speed than Magneton) if there are compelling reasons
An Evolution in general has stats which maintain it's Offensive/Defensive and Physical/Special ratios, but clearly there are exceptions to this as well.
An Evolution in general maintains its current type or, if monotyped, gains a secondary type. In rare cases, a dual-typed Pokemon may evolve one of its types into a different type.
So basically every rule has exceptions, so take it more like a guide than writ in stone.