Level Up Bonuses
Any% 2.01 Level Up Route
Mario: SP every level except 6, 9, 12 (ATK)
Peach: SP every level except 10 (HP)
Geno: ATK every level except 7, 8 (HP)
Mallow: HP every level except 3, 4, and 5 (ATK, HP, ATK)
Bowser: ATK on levels 9, 11, 12, and 14, HP otherwise
If your EXP ever deviates and your levelups happen out of order from when the chart says they should happen, you can memorize these patterns:
Always give HP to characters who aren't being used anymore, since their stats are irrelevant and HP is the quickest (default) to select.
Mario is always SP to power up his jump moves, except on some multiples of 3, which tend to give better ATK bonuses.
Geno is very weak before Yaridovich, so give him HP for 7 and 8 so he can survive Water Blast. Then always give him ATK.
Bowser is always ATK before he is retired, except at 10 and 13, which give high HP bonuses. He needs HP for Countdown.
Peach's first levelup is HP for survival, then SP every level afterward.
No Super Suit Level Up Route
Mario: SP every level except 4 and 6 until level 9, then all ATK with SP every third level (11, 14, 17, 20).
Peach: SP first two levels (10, 11), then ATK/HP/SP cycle in order twice (up to 17), then ATK for the rest.
Geno: ATK every level except 7, 8, 16 (HP)
Mallow: 3 (SP), 4/5 (ATK), then HP for the rest of the game (not used again).
Bowser: ATK every level until Valentina, then HP (not used again).
Notes: You do two ability swaps in the run.
The first ability swap is the same as the Any% route, in the Sea you will select HP for Level 7 Peach (which is really Mallow) and select SP for Level 10 Mallow (which is really Peach).
The second ability swap is during the death abuse loop in Land's End. On the first star of the third cycle, you will swap Mallow and Peach and select SP for Level 14 Mallow (which is really Peach). Peach will learn Snowy for this route, instead of Geno Blast for the Any% route.
Safe Strats Level Up Route
Mario: All ATTACK except levels 2, 3, 5, 8 do MAGIC
Peach: All MAGIC except level 10 do HP (first level-up)
Geno: All ATTACK except levels 7, 8 do HP (first two level-ups)
Mallow: All MAGIC except levels 3, 4 do ATTACK (first two level-ups)
Bowser: All ATTACK