PP Up
Johto: Route 39 (With Dowsing MCHN), Violet City, Radio Tower (Goldenrod Lottery Prize - 2 Numbers Match), Mt. Mortar, Tin Tower, Ice Path, Pokeathlon Dome (With Dowsing MCHN)
Kanto: Route 15, Pewter City (With Dowsing MCHN), Celadon City (With Dowsing MCHN), Cerulean Cave, Cerulean Cave (With Dowsing MCHN), Rock Tunnel
Elixir
Johto: Route 44 (With Dowsing MCHN), Route 45, Union Cave, Mt. Mortar, Mt. Mortar, Dark Cave (With Dowsing MCHN)
Kanto: Route 2, Route 9 (With Dowsing MCHN), Route 12 (With Dowsing MCHN), Rock Tunnel
Ether
Johto: Goldenrod City (Dept. Store Basement), Ecruteak City (With Dowsing MCHN), Ilex Forest, Ilex Forest (With Dowsing MCHN), Mt. Mortar, Burnt Tower (With Dowsing MCHN), Shining Lighthouse
Max Elixir
Johto: Mt. Silver
Kanto: Route 17 (With Dowsing MCHN), Cerulean Cave
Max Ether
Johto: Route 41 (With Dowsing MCHN), Route 43, Violet City, Cianwood City, Ruins of Alph, Mt. Mortar, Dark Cave, Mt. Silver (With Dowsing MCHN), Goldenrod Underground, The Cliff Cave
Kanto: Route 17, Route 19, Vermillion City, Viridian Forest (With Dowsing MCHN), Rock Tunnel, Victory Road
Leppa Berry
Johto: Violet City (Give Juggler a Red Shard), Ruins of Alph (Bottom Left), Ruins of Alph (Top Left)
The Max Elixir fully restores the PP of all moves of a single Pokemon.
Source: Serebii ItemDex