Based on Flavor: Fennekin: Flash Fire Explanation: Fennekin has no real outstanding features that pertain to any abilities, so I decided to work with his Fire typing and go for Flash Fire. Froakie: Inner Focus Explanation: Froakie is a Ninja. Ninjas have focus. Chespin: Overcoat Explanation: Chespin's hood thing looks like an overcoat.
Based on Viability: Fennekin: Magic Guard Explanation: Fennekin is Fire type, leaving it SR weak. Magic Guard patches that up to an immunity AND it makes sense, because Fennekin will be a psychic type (probably) and Magic Guard is most common among psychic types. Magic Guard is a great ability, and allows Fennekin to run Life Orb with no drawbacks, so it'll have a great chance of becoming a powerful sweeper or wall breaker. Froakie: Hydration Explanation: Immunity to status in rain is great - but being healed of status at the end of each turn is even better! This way, Froakie can run rest on any set safely whilst not having to worry about other status afflictions. Chespin Harvest Harvest is a cool ability with very few viable users. Chespin will undoubtably have decent stats, and has an okay(ish) defensive type. From what we've seen, it's also the most defensive of the starters (certainly the slowest) so the two abilities fit hand in hand. Sitrus or Lum, Chespin could become a great sun wall... even if it's relegated to lower tiers.