Where to catch Pichu

In Paldea (Scarlet & Violet)

• Los Platos — Walk
• South Province (Area One) — Walk
• South Province (Area Two) — Walk

In Kitakami (Scarlet & Violet – The Teal Mask)

• Apple Hills — Walk
• Crystal Pool — Walk
• Infernal Pass — Walk
• Kitakami Road — Walk
• Loyalty Plaza — Walk
• Oni Mountain — Walk
• Oni's Maw — Walk
• Reveler's Road — Walk
• Wistful Fields — Walk

In Johto & Kanto (Gold, Silver & Crystal)

• Route 34 — Gift, Walk

Pichu — full Pokédex entry