1 The art style - Legend Of Zelda: Wind Waker to Twilight Princess
2 Brinstar - Metroid to Super Metroid
3 Porky's physical age - Earthbound to Mother 3
4 The main reason for the game being difficult - Castlevania to Castlevania 2: Simon's Quest
5 The gameplay style - Zelda 1 to Zelda 2
6 Handsome Jack - Borderlands: The Pre-Sequel to Borderlands 2
7 Hyrule - Original Legend Of Zelda to Breath Of The Wild and Wind Waker
8 Chop Chop Master Onion's social status - Parappa The Rapper to Um Jammer Lammy
9 The overall amount of presence that the main villain had in the storyline - Legend Of Zelda: Ocarina Of Time to Majora's Mask
10 Carmelita Fox's voice - Sly Cooper And The Thievius Raccoonus to Sly 3: Honor Among Thieves
11 Uka-Uka's and Aku-Aku's character designs - Crash Bandicoot Trilogy to Crash Of The Titans
Crash of the Titans is garbage, and it is the biggest insult to the Crash Bandicoot Trilogy.
This isn't unfortunate, since the crash trilogy and crap of the titans were not made by the same game developers.
12 Planet Orxon's environmental status - Ratchet & Clank to Ratchet Deadlocked
It was polluted and now it's not? How?
13 Jim's method of hovering in midair and swinging from things - Earthworm Jim 2
14 Chop Chop Master Onion's occupation - Parappa The Rapper to Parappa The Rapper 2
15 The gameplay style - Paper Mario to Super Paper Mario
16 The gameplay and graphical styles - Another Metroid 2 Remake to Metroid: Samus Returns
17 The main protagonist - Donkey Kong Country to Donkey Kong Country 3: Dixie's Double Trouble
18 The general tone of the game - Conker's Pocket Tales to Conker's Bad Fur Day
No one saw Conker's adult form coming!
19 How often the player was allowed to use Hyper Mode - Metroid Prime to Metroid Prime 3: Corruption
20 The overall tone of the game - Earthbound to Mother 3
21 GLaDOS - Portal to Portal 2
22 Togami's physical fitness and attitude towards other people - Danganronpa 1 to Danganronpa 2
23 Chairman Drek - Ratchet & Clank (2002) to Ratchet & Clank (2016)
24 Bowser - Super Mario Bros to the Mario RPGs
25 Luigi - Super Mario Bros to Luigi's Mansion