Really? I was surprised it fell that much. I figured it would still be top 5 this month.

Top for this past month was FF7!
I'll update the missing months at a later date...

March 2019
1. Final Fantasy VII
2. Baba Is You
3. Mario + Rabbids Kingdom Battle
4. Stardew Valley
5. New Super Mario Bros. U Deluxe
6. Minecraf
7. Final Fantasy IX
8. Yoshi’s Crafted World
9. Overcooked: Special Edition
10. Fear Effect Sedna
11. Hollow Knight
12. Mario Kart 8 Deluxe
13. Cuphead
14. World of Final Fantasy Maxima
15. Splatoon 2

Source

Hurray for FFVII! Why is Mario + Rabbids selling so well on the eShop? Did it receive a discount?

Yeah, it did, twice in fact if I remember correctly: Once as a normal promo and tehn also during Mar10 Day. In any case, that game deserves those sales imo

2018 TOP DOWNLOADS

December 2018
1. Super Smash Bros. Ultimate
2. Mario + Rabbids Kingdom Battle
3. Super Mario Party
4. Crypt of the NecroDancer: Nintendo Switch Edition
5. Mario Kart 8 Deluxe
6. Gris
7. Stardew Valley
8. Octopath Traveler
9. Minecraft
10. Crash Bandicoot N.Sane Trilogy
11. Pokemon: Let’s Go, Pikachu
12. Civilization VI
13. Overcooked 2
14. FIFA 19
15. Diablo III: Eternal Collection

November 2018
1. Pokemon: Let’s Go, Pikachu
2. Pokemon: Let’s Go, Eevee
3. Diablo III – Eternal Collection
4. Super Smash Bros. Ultimate
5. Super Mario Odyssey
6. Rocket League
7. Super Mario Party
8. Enter the Gungeon
9. Civilization VI
10. Zelda: Breath of the Wild
11. Undertale
12. Stardew Valley
13. Donkey Kong Country: Tropical Freeze
14. Moonlighter
15. Mario Kart 8 Deluxe

October 2018
1. Super Mario Party
2. Dark Souls: Remastered
3. Undertale
4. Overcooked: Special Edition
5. The Binding of Isaac: Afterbirth+
6. Overcooked 2
7. Stardew Valley
8. Mega Man 11
9. Hollow Knight
10. Minecraft
11. Bulb Boy
12. The Way Remastered
13. Dead Cells
14. FIFA 19
15. Mario Kart 8 Deluxe

September 2018
1. Undertale
2. Mario Kart 8 Deluxe
3. Final Fantasy XV Pocket Edition
4. Hollow Knight
5. Dead Cells
6. Super Mario Party
7. Rocket League
8. Into the Breach
9. Human: Fall Flat
10. Stardew Valley
11. Overcooked 2
12. Minecraft
13. Cities: Skylines
14. Brawl
15. Surgeon Simulator CPR

August 2018
1. Hollow Knight
2. Dead Cells
3. Overcooked 2
4. Okami HD
5. Mario Kart 8 Deluxe
6. Minecraft
7. Stardew Valley
8. Octopath Traveler
9. Salt and Sanctuary
10. Monster Hunter Generations Ultimate
11. Rocket League
12. Into the Breach
13. Arcade Archives Vs. Super Mario Bros.
14. Owlboy
15. Enter the Gungeon

July 2018
1. Octopath Traveler
2. Hollow Knight
3. Enter the Gungeon
4. FIFA 18
5. Mario Tennis Aces
6. Crash Bandicoot N. Sane Trilogy
7. Minecraft
8. Captain Toad: Treasure Tracker
9. Stardew Valley
10. Mario Kart 8 Deluxe
11. Dead Cells
12. Arcade Archives Vs. Super Mario Bros.
13. Rocket League
14. Mega Man X Legacy Collection
15. Plague Road

June 2018
1. Hollow Knight
2. FIFA 18
3. Mario Tennis Aces
4. Minecraft
5. Splatoon 2
6. Astro Bears Party
7. Stardew Valley
8. Overcooked Special Edition
9. Crash Bandicoot N. Sane Trilogy
10. Rocket League
11. Paladins
12. Golf Story
13. Wizard of Legend
14. Mario Kart 8 Deluxe
15. Arcade Archives Vs. Super Mario Bros.

May 2018
1. Donkey Kong Country: Tropical Freeze
2. FIFA 18
3. Stardew Valley
4. Wizard of Legend
5. Minecraft: Nintendo Switch Edition
6. Rocket League
7. Hyrule Warriors: Definitive Edition
8. Wonder Boy: The Dragon’s Trap
9. Arcade Archives Vs. Super Mario Bros.
10. Bloodstained: Curse of the Moon
11. 60 Seconds!
12. Timberman VS
13. Death Road to Canada
14. Yonder: The Cloud Catcher Chronicles
15. Mega Man Legacy Collection

April 2018
1. Minecraft: Nintendo Switch Edition
2. Rocket League
3. Stardew Valley
4. Football Manager Touch 2018
5. Arcade Archives Vs. Super Mario Bros.
6. Kirby Star Allies
7. Shovel Knight: Treasure Trove
8. Oxenfree
9. Don’t Star: Nintendo Switch Edition
11. Robonauts
12. The Elder Scrolls V: Skyrim
13. Celeste
14. Naruto Shippuden: Ultimate Ninja Storm Trilogy
15. Super Mario Odyssey

March 2018
1. Rocket League
2. Minecraft: Nintendo Switch Edition
3. Kirby Star Allies
4. Stardew Valley
5. Arcade Archives Vs. Super Mario Bros.
6. The Elder Scrolls V: Skyrim
7. Celeste
8. Super Bomberman R
9. Mario Kart 8 Deluxe
10. SteamWorld Dig
11. Fe
12. FIFA 18
13. Thimbleweed Park
14. Super Mario Odyssey
15. Wonder Boy: The Dragon’s Trap

February 2018
1. Rocket League
2. Minecraft: Nintendo Switch Edition
3. Celeste
4. Stardew Valley
5. FIFA 18
6. Arcade Archives Vs. Super Mario Bros.
7. Bayonetta
8. Overcooked: Special Edition
9. Enter the Gungeon
10. Bayonetta 2
11. Dragon Quest Builders
12. Oxenfree
13. Mario Kart 8 Deluxe
14. Human: Fall Flat
15. Worms W.M.D

January 2018
1. Oxenfree
2. Minecraft: Nintendo Switch Edition
3. Arcade Archives Vs. Super Mario Bros.
4. Stardew Valley
5. Rocket League
6. Mario Kart 8 Deluxe
7. NBA Playgrounds: Enhanced Edition
8. The Escapists 2
9. Enter the Gungeon
10. Super Mario Odyssey
11. Celeste
12. 1-2 Switch
13. Super Meat Boy
14. Sonic Mania
15. Overcooked: Special Edition

Final Fantasy VII doing that well is no surprise. We Nintendo fans have been waiting for this game for 22 years.

look out plumber-boy, mustache-man. your worse nightmare has arrived.

What a surprise... it's Cuphead this time around.

April 2019
1. Cuphead
2. Super Mario Odyssey
3. The Elder Scrolls V: Skyrim
4. Enter the Gungeon
5. Zelda: Breath of the Wild
6. Final Fantasy VII
7. Rocket League
8. Rayman Legends: Definitive Edition
9. Minecraft
10. FIFA 19
11. Mario + Rabbids Kingdom Battle
12. Overcooked 2
13. Stardew Valley
14. Dragon’s Dogma: Dark Arisen
15. Octopath Traveler

Source

And Skyrim on third spot.

I'm a bit surprised by the lack of new games on the list other than Cuphead. Weren't the Phoenix Wright trilogy and Hellblade near the top of the eShop weekly chart most of the month? (I live in the US so maybe it's different here)