In my Rhunaria homebrew, planetouched are represented by four templates, each giving +1 ECL and CR. My templates are mostly like the printed versions of the aasimar, tiefling, chaond, and zenythri, but a little beefed up to be more worthy of their ECL. I'll post the tiefling here as an example; I'll leave out the obvious bits about the creature changing into an Outsider in type. Of my planetouched versions, only chaonds and zenythri have -2 Cha, as the lawful neutral or chaotic neutral Outsiders they're descended from have comparatively-alien mindsets and a poor affinity for sorcery.
Tiefling Template
The distant descendant of an intelligent fiend and a mortal, after generations of mixing with mortal bloodlines. The tiefling is mostly mortal, but has some discernable qualities leading back to his or her fiendish forebearer. This may be a vaguely leathery or scaly quality to his or her skin, eyes of pure red or black, small ridged horns, unsettling hair or eye colors, a sinister echo to their voice, animal-like ears, dark fur in some places, a vile skin tone, a vestigial tail and vestigial bat wings, slimy perpetual sweat, black blood (lending a dark grayish hue to their veins and arteries), or a perpetual odor of sulfur or other such stench, for instance. In Rhunaria, the term 'fiend' refers to any kind of extraplanar being of the Outsider type who also bears the Evil subtype, meaning that they are native to the lower planes of vice. This template may be applied to any corporeal living creature who does not otherwise possess the Outsider type, and who does not have the aasimar, anarchic, axiomatic, celestial, chaond, half-anarchial, half-axion, half-celestial, half-fiend, fiendish, or zenythri templates.
Special Attacks: A tiefling has all the special attacks of the base creature, plus gaining the supernatural ability of Darkness useable once per day, functioning as per the sorcerer spell, at a caster level equal to their total number of hit dice.
Special Qualities: A tiefling has all the special qualities of the base creature, plus Darkvision 60 feet (seeing perfectly in natural darkness out to this range, but Darkvision sees only in shades of gray) if they do not have equal or superior Darkvision already. Tieflings, as Outsiders, cannot be raised or resurrected, though a Wish or Miracle can bring them back to life. Additionally, a tiefling has Cold Resistance 5, Electricity Resistance 5, and Fire Resistance 5, or increases any such resistances of the base creature by 5 points. Tieflings gain a +2 racial bonus on Bluff and Hide checks, and on saving throws against charms or poison. Also, tieflings can see through unnatural darkness (such as from a Darkness or Deeper Darkness spell or ability) with their darkvision, as a supernatural benefit.
Abilities: The tiefling has the following ability score adjustments, in addition to those of the base creature: +2 Dexterity, +2 Intelligence.
Challenge Rating: Same as the base creature, but add +1 to the CR if the base creature has 5 or more racial hit dice and was not already a Dragon or Outsider in type. If the base creature has a CR lower than 1, instead increase its CR one degree; CR 1/2 would become CR 1, CR 1/3 would become 1/2, CR 1/4 would become CR 1/3, and CR 1/6 would become CR 1/4.
Effective Character Level: A tiefling has an Effective Character Level (ECL) adjustment of +1, in addition to any that the base creature already has. This means that a tiefling is equivalent in power to a character 1 level higher than their actual character level or hit dice.
