Revolutionary changes in Pokémon games through the ages, in no particular order:

• Physical-Special move division
• The various EV training facilitators
• Wireless communications and Internet connection
• Hypertraining
• HM Emancipation
• Quick-use Repel
• Move Tutors
• Type effectiveness indicators
• Mega Evolution and Z Energy
• Trainer customization

What is yet to come:

• Skippable tutorials
• Circumstantial auto-save