If I put a Skeledirge (Stage 2) directly into play using Tatsugiri ex's "Cinnabar Lure" attack and I also have a Victini with "Victory Cheer" Ability in play, will Skeledirge's attacks do 10 more damage?
Yes. Although Skeledirge is not an "Evolved Pokemon" in this scenario, it is still considered an "Evolution Pokemon" (Stage 2) that meets the requirements for Victory Cheer.
Source: Surging Sparks FAQ; TPCi Rules Team (2024-11-07)

Relevant cards

Note: All applicable cards may not be listed below.
SV8_142
SV8_142
SV8_21
SV8_21