Info order Type/Name/Ace Pokemon/pokemon that can help you/Difficulty(my opinion)
first gym: Poison/Venam/Seviper/Woobat,swoobat/medium
second gym:Fighting/Sensei Keta/Lucario/woobat,swoobat,fire type for ace,dont use shadow pokemon/Medium
third gym:Normal/Marianette/Slaking/Anything with figthing moves can take em out fast/Easy fourth gym:Ghost/Narcissa/Mismagius/Pangoro,pancham with scrappy does wonders/Real Hard
fifth gym:Water/Valarie/Milotic/Mareep evos in hotel for free/hard
sixth gym:Bug/Crawli/Volcarona/Fire,electric,rock,Ampharos can learn most by leveling up/Pushover
Puzzles and where to get most of these guys are up too you not too mention some real hard bosses in between so good luck