1.Stats: Should Dedenne get a stat boost, Evolution, Mega Evolution or nothing?
Dedenne can get at most +119 BST, however Dedenne already has 431 BST which is close to the highest Pikaclone BST, Togedemaru's 435 BST.
Dedenne would love an Evolution, but since Pikachu exists, it is unlikely that there will be a Pikaclone with an evolution. However, Dedenne's BST is high enough to varrant only one Evolution. A Mega would be worthless and pointless, especially now that Tapu Koko exists.
2.Should Dedenne get more abilities?
Yes. Lightningrod, Electric Surge, Misty Surge, Volt Absorb, Motor Drive, Static, Friend Guard, Technician, Competitive etc. etc. etc.
3. Should Dedenne get more moves?
Slack Off and
DAZZLING GLEAM are options. Moonblast, Draining Kiss, Sweet Kiss, Fake Tears and Switcheroo are also options. Calm Mind and Nasty Plot are also options.
4.What additional typing Dedenne can have?
Normal, Steel and Psychic are options. Dark, Ground, and Grass are also options.